Method and arrangement for mapping a road

ABSTRACT

Arrangement and method for mapping a road during travel of a vehicle having two data acquisition modules arranged on sides of the vehicle, each including a GPS receiver and antenna for enabling the vehicle&#39;s position to be determined and a linear camera which provides one-dimensional images of an area on the respective side in a vertical plane perpendicular to the road such that information about the road is obtained from a view in a direction perpendicular to the road. A processor unit forms a map database of the road by correlating the vehicle&#39;s position and the information about the road. Instead of or in addition to the linear cameras, scanning laser radars are provided and transmit waves downward in a plane perpendicular to the road and receive reflected waves to provide information about distance between the laser radars and the ground for use in forming the database.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to on the grounds that it includes commonsubject matter as, but does not claim priority from, U.S. patentapplication Ser. No. 09/679,317 filed Oct. 4, 2000. U.S. patentapplication Ser. No. 09/523,559 filed Mar. 10, 2000 and U.S. patentapplication Ser. No. 09/177,041 filed Oct. 22, 1998.

BACKGROUND OF THE INVENTION Field of the Invention

This invention is in the fields of automobile safety, intelligenthighway safety systems, accident avoidance, accident elimination,collision avoidance, blind spot detection, anticipatory sensing,automatic vehicle control, intelligent cruise control, vehiclenavigation and other automobile, truck and train safety, navigation andcontrol related fields.

The invention relates generally to methods for mapping a road in which avehicle-mounted arrangement is used and the vehicle-mounted arrangement.

The invention also relates generally to an apparatus and method forprecisely determining the location and orientation of a host vehicleoperating on a roadway and location of multiple moving or fixedobstacles that represent potential collision hazards with the hostvehicle to thereby eliminate collisions with such hazards. In the earlystages of implementation of the apparatus and method and when collisionswith such hazards cannot be eliminated, the apparatus and method willgenerate warning signals and initiate avoidance maneuvers to minimizethe probability of a collision and the consequences thereof. Moreparticularly, the invention relates to the use of a Global PositioningSystem (“GPS”), differential GPS (“DGPS”), other infrastructure-basedlocation aids, cameras, radar and laser radar and an inertial navigationsystem as the primary host vehicle and target locating system withcentimeter accuracy. The invention is further supplemented by a digitalcomputer system to detect, recognize and track all relevant potentialobstacles, including other vehicles, pedestrians, animals, and otherobjects on or near the roadway. More particularly, the invention furtherrelates to the use of centimeter-accurate maps for determining thelocation of the host vehicle and obstacles on or adjacent the roadway.Even more particularly, the invention further relates to aninter-vehicle and vehicle to infrastructure communication systems fortransmitting GPS and DGPS position data, as well as, relevant targetdata to other vehicles for information and control action, The presentinvention still further relates to the use of neural networks andneural-fuzzy rule sets for recognizing and categorizing obstacles andgenerating and developing optimal avoidance maneuvers where necessary.

Automobile accidents are one of the most serious problems facing societytoday, both in terms of deaths and injuries, and in financial lossessuffered as a result of accidents. The suffering caused by death orinjury from such accidents is immense. The costs related to medicaltreatment, permanent injury to accident victims and the resulting lossof employment opportunities, and financial losses resulting from damageto property involved in such accidents are staggering. Providing theimproved systems and methods to eventually eliminate these deaths,injuries and other losses deserves the highest priority. The increase inpopulation and use of automobiles worldwide with the concomitantincreased congestion on roadways makes development of systems forcollision elimination even more urgent. While many advances have beenmade in vehicle safety, including, for example, the use of seatbelts,airbags and safer automobile structures, much room for improvementexists in automotive safety and accident prevention systems.

There are two major efforts underway that will significantly affect thedesign of automobiles and highways. The first is involved withpreventing deaths and serious injuries from automobile accidents. Thesecond involves the attempt to reduce the congestion on highways. In thefirst case, there are approximately forty two thousand (42,000) peoplekilled each Year in the United States by automobile accidents andanother several hundred thousand are seriously injured. In the secondcase, hundreds of millions of man-hours are wasted every year by peoplestuck in traffic jams on the world's roadways. There have been manyattempts to solve both of these problems; however, no single solutionhas been able to do so.

When a person begins a trip using an automobile, he or she first entersthe vehicle and begins to drive, first out of the parking space and thentypically onto a local or city road and then onto a highway. In leavingthe parking space, he or she may be at risk from an impact of a vehicletraveling on the road. The driver must check his or her mirrors to avoidsuch an event and several electronic sensing systems have been proposedwhich would warn the driver that a collision is possible. Once on thelocal road, the driver is at risk of being impacted from the front, sideand rear, and electronic sensors are under development to warn thedriver of such possibilities. Similarly, the driver may run into apedestrian, bicyclist, deer or other movable object and various sensorsare under development that will warn the driver of these potentialevents. These various sensors include radar, optical, infrared,ultrasonic. and a variety of others sensors, each of which attempts tosolve a particular potential collision event. It is important to notethat in none of these cases is there sufficient confidence in thedecision that the a control of the vehicle is taken away from thedriver. Thus, action by the driver is still invariably required.

In some proposed future Intelligent Transportation System (ITS) designs,hardware of various types is embedded into the highway and sensors whichsense this hardware are placed onto the vehicle so that it can beaccurately guided along a lane of the highway. In various other systems,cameras are used to track lane markings or other visual images to keepthe vehicle in its lane. However, for successful ITS, additionalinformation is needed by the driver, or the vehicle control system, totake into account weather, road conditions, congestion etc., whichtypically involves additional electronic hardware located on orassociated with the highway as well as the vehicle. From thisdiscussion, it is obvious that a significant number of new electronicsystems are planned for installation onto automobiles. However, to date,no product has been proposed or designed which combines all of therequirements into a single electronic system. This is the intent of thisinvention.

The safe operation of a vehicle can be viewed as a process in theengineering sense. To achieve safe operation, first the process must bedesigned and then a vehicle control system must be designed to implementthe process. The goal of a process designer is to design the process sothat it does not fail. The fact that so many people are being seriouslyinjured and killed in traffic accidents and the fact that so much timeis being wasted in traffic congestion is proof that the current processis not working and requires a major redesign. To design this new processthe information required by the process must be identified, the sourceof that information determined and the process designed so that thesources of information can communicate effectively to the user of theinformation, which will most often be a vehicle control system. Finally,the process must have feedback that self-corrects the process when it istending toward failure.

Although it is technologically feasible, it is probably sociallyunacceptable at this time for a vehicle safety system to totally controlthe vehicle. The underlying premise of this invention, therefore, isthat people will continue to operate their vehicle and control of thevehicle will only be seized by the control system when such an action isrequired to avoid an accident or when such control is needed for theorderly movement of vehicles through potentially congested areas on aroadway. When this happens, the vehicle operator will be notified andgiven the choice of exiting the road at the next opportunity. In someimplementations, especially when this invention is first implemented ona trail basis, control will not be taken away from the vehicle operatorbut a warning system will alert the driver of a potential collision,road departure or other infraction.

Let us consider several scenarios and what information is required forthe vehicle control process to prevent accidents. In one case, a driveris proceeding down a country road and falls asleep and the vehiclebegins to leave the road, perhaps heading toward a tree. In this case,the control system would need to know that the vehicle was about toleave the road and for that it must know the position of the vehiclerelative to the road. One method of accomplishing this would be to placea wire down the center of the road and to place sensors within thevehicle to sense the position of the wire relative to the vehicle. Analternate approach would be for the vehicle to know exactly where it ison the surface of the earth and to also know exactly where the edge ofthe road is.

These approaches are fundamentally different because in the formersolution every road in the world would require the placement ofappropriate hardware as well as the maintenance of this hardware. Thisis obviously impractical. In the second case, the use of the globalpositioning satellite system (GPS), augmented by additional systems tobe described below, will provide the vehicle control system with anaccurate knowledge of its location. Whereas it would be difficult toinstall and maintain hardware such as a wire down the center of the roadfor every road in the world, it is not difficult to survey every roadand record the location of the edges, and the lanes for that matter, ofeach road. This information must then be made available through one ormore of a variety of techniques to the vehicle control system.

Another case might be where a driver is proceeding down a road anddecides to change lines while another vehicle is in the driver's blindspot. Various companies are developing radar, ultrasonic or opticalsensors to warn the driver if the blind spot is occupied. The driver mayor may not heed this warning, perhaps due to an excessive false alarmrate, or he or she may have become incapacitated, or the system may failto detect a vehicle in the blind spot and thus the system will fail.

Consider an alternative technology where again each vehicle knowsprecisely where it is located on the earth surface and additionally cancommunicate this information to all other vehicles within a certainpotential danger zone relative to the vehicle. Now, when the driverbegins to change lanes, his or her vehicle control system knows thatthere is another vehicle in the blind spot and therefore will eitherwarn the driver or else prevent him or her from changing lanes therebyavoiding the accident.

Similarly, if a vehicle is approaching a stop sign or red traffic lightand the operator fails to bring the vehicle to a stop, if the existenceof this traffic light or stop sign has been made available to thevehicle control system, the system can warn the driver or seize controlof the vehicle to stop the vehicle and prevent a potential accident.Additionally, if an operator of the vehicle decides to proceed across anintersection without seeing an oncoming vehicle, the control system willonce again know the existence and location and perhaps velocity of theoncoming vehicle and warn or prevent the operator from proceeding acrossthe intersection.

Consider another example where water on the surface of a road isbeginning to freeze. Probably the best way that a vehicle control systemcan know that the road is about to become slippery, and therefore thatthe maximum vehicle speed must be significantly reduced, is to getinformation from some external source. This source can be sensorslocated on the highway that are capable of determining this conditionand communicating it to the vehicle. Alternately, the probability oficing occurring can be determined analytically from meteorological dataand a historical knowledge of the roadway and communicated to thevehicle over a LEO satellite system, the Internet or an FM sub-carrieror other means. A combination of these systems can also be used.

Studies have shown that a combination of meteorological and historicdata can accurately predict that a particular place on the highway willbecome covered with ice. This information can be provided to properlyequipped vehicles so that the vehicle knows to anticipate slipperyroads. For those roads that are treated with salt to eliminate frozenareas, the meteorological and historical data will not be sufficient.Numerous systems are available today that permit properly equippedvehicles to measure the coefficient of friction between the vehicle'stires and the road. It is contemplated that perhaps police or otherpublic vehicles will be equipped with such a friction coefficientmeasuring apparatus and can serve as probes for those roadways that havebeen treated with salt. Information from these probe vehicles will befed into the information system that will then be made available tocontrol speed limits in the those areas.

Countless other examples exist, however, from those provided above itcan be seen that for the vehicle control system to function withouterror, certain types of information must be accurately provided. Theseinclude information permitting the vehicle to determine its absolutelocation and means for vehicles near each other to communicate thislocation information to each other. Additionally, map information thataccurately provides boundary and lane information of the road must beavailable. Also, critical weather or road-condition information isnecessary. The road location information need only be generated once andchanged whenever the road geometry is altered. This information can beprovided to the vehicle through a variety of techniques includingprerecorded media such as CD-ROM or DVD disks or through communicationsfrom transmitters located in proximity to the vehicle, satellites, radioand cellular phones.

Consider now the case of the congested highway. Many roads in the worldare congested and are located in areas where the cost of new roadconstruction is prohibitive or such construction is environmentallyunacceptable. It has been reported that an accident on such a highwaytypically ties up traffic for a period of approximately four times thetime period required to clear the accident. Thus, by eliminatingaccidents, a substantial improvement of the congested highway problemresults. This of course is insufficient. On such highways, each vehicletravels with a different spacing, frequently at different speeds and inthe wrong lanes. If the proper spacing of the vehicles could bemaintained, and if the risk of an accident could be substantiallyeliminated, vehicles under automatic control could travel atsubstantially higher velocities and in a more densely packedconfiguration thereby substantially improving the flow rate of vehicleson the highway by as much as a factor of 3 to 4 times. This not onlywill reduce congestion but also improve air pollution. Once again, ifeach vehicle knows exactly where it is located, can communicate itslocation to surrounding vehicles and knows precisely where the road islocated, then the control system in each vehicle has sufficientinformation to accomplish this goal.

Again the intent of the system and process described here is to totallyeliminate automobile accidents as well as reduce highway congestion.This process is to be designed to have no defective decisions. Theprocess employs information from a variety of sources and utilizes thatinformation to prevent accidents and to permit the maximum vehiclethroughput on highways.

The information listed above is still insufficient. The geometry of aroad or highway can be determined once and for all, until erosion orconstruction alters the road. Properly equipped vehicles can know theirlocation and transmit that information to other properly equippedvehicles. There remains a variety of objects whose location is notfixed, which have no transmitters and which can cause accidents. Theseobjects include broken down vehicles, animals such as deer which wanderonto highways, pedestrians, bicycles, objects which fall off of trucks,and especially other vehicles which are not equipped with locationdetermining systems and transmitters for transmitting that informationto other vehicles. Part of this problem can be solved for congestedhighways by restricting access to these highways to vehicles that areproperly equipped. Also, these highways are typically in urban areas andaccess by animals can be effectively eliminated. Heavy fines can beimposed on vehicles that drop objects onto the highway. Finally. sinceevery vehicle and vehicle operator becomes part of the process, eachsuch vehicle and operator becomes a potential source of information tohelp prevent catastrophic results. Thus, each vehicle should also beequipped with a system of essentially stopping the process in anemergency. Such a system could be triggered by vehicle sensors detectinga problem or by the operator strongly applying the brakes, rapidlyturning the steering wheel or by activating a manual switch when theoperator observes a critical situation but is not himself in immediatedanger. An example of the latter case is where a driver witnesses a boxfalling off of a truck in an adjacent lane.

To solve the remaining problems, therefore, each vehicle should also beequipped with an anticipatory collision sensing system, or collisionforecasting system, which is capable of identifying or predicting andreacting to a pending accident. As the number of vehicles equipped withthe control system increases, the need for the collision forecastingsystem will diminish.

Once again, the operator will continue to control his vehicle providedhe or she remains within certain constraints. These constraints are likea corridor. As long as the operator maintains his vehicle within thisallowed corridor, he or she can operate that vehicle withoutinterference from the control system. That corridor may include theentire width of the highway when no other vehicles are present or it maybe restricted to all eastbound lanes, for example. In still other cases,that corridor may be restricted to a single line and additionally, theoperator may be required to keep his vehicle within a certain spacingtolerance from the preceding vehicle. If a vehicle operator wishes toexit a congested highway, he could operate his turn signal that wouldinform the control system of this desire and permit the vehicle tosafely exit from the highway. It can also inform other adjacent vehiclesof the operator's intent, which could then automatically cause thosevehicles to provide space for lane changing, for example. The highwaycontrol system is thus a network of individual vehicle control systemsrather than a single highway resident computer system.

U.S. Department of Transportation (DOT) Policy

In the DOT. FY 2000 Budget in Brief Secretary Rodney Slater states that“Historic levels of federal transportation investment . . . are proposedin the FY 2000 budget.” Later, Secretary Slater states that“Transportation safety is the number one priority.” DOT has estimatedthat $165 billion per year are lost in fatalities and injuries on U.S.roadways. Another $50 billion are lost in wasted time of people oncongested highways. Presented herein is a plan to eliminate fatalitiesand injuries and to substantially reduce congestion. The total cost ofimplementing this plan is minuscule compared to the numbers statedabove. This plan has been named “The Road to Zero Fatalities™”, or RtZF™for short.

In the DOT Performance Plan FY 2000. Strategic Goal: Safety, it isstated that “The FY 2000 budget process proposes over $3.4 billion fordirect safety programs to meet this challenge.” The challenge is to“Promote the public health and safety by working toward the eliminationof traffic related deaths, injuries and property damage”. The goal ofthe RtZF is the same and herein a plan is presented for accomplishingthis goal. The remainder of the DOT discussion centers around wishfulthinking to reduce the number of transportation related deaths,injuries, etc. However, the statistics presented show that in spite ofthis goal, the number of deaths is now increasing. As discussed below,this is the result of a failed process.

Reading through the remainder of the DOT Performance Plan FY 2000, oneis impressed by the billions of dollars that are being spent to solvethe highway safety problem coupled with the enormous improvement thathas been made until the last few years. It can also be observed that theincrease in benefits from these expenditures has now disappeared. Forexample, the fatality rate per 100 million vehicle miles traveled fellfrom 5.5 to 1.7 in the period from the mid-1960s to 1994. But thisdecrease has now substantially stopped! This is an example of the law ofdiminishing returns and signals the need to take a totally new approachto solving this problem.

U.S. Intelligent Vehicle Initiative (IVI) Policy

Significant funds have been spent on demonstrating various ITStechnologies. It is now time for implementation. With over 40,000fatalities and almost four million people being injured every year on USroadways, it is time to take affirmative action to stop this slaughter.The time for studies and demonstrations is past. However, the deploymentof technologies that are inconsistent with the eventual solution of theproblem will only delay implementation of the proper systems and therebyresult in more deaths and injuries.

A primary goal of the Intelligent Vehicle Initiative is to reducehighway related fatalities per 100 million vehicle miles traveled from1.7 in 1996 to 1.6 in 2000. Of course the number of fatalities may stillincrease due to increased road use. If this reduction in fatalitiescomes about due to slower travel speeds, because of greater congestion,then has anything really been accomplished? Similar comments apply tothe goal of reducing the rate of injury per 100 million vehicle milesfrom 141 in 1996 to 128 in 2000. An alternate goal is to have thetechnology implemented on all new vehicles by the year 2010 that willeventually eliminate all fatalities and injuries. As an intermediatemilestone, it is proposed to have the technology implemented on all newvehicles by 2007 to reduce or eliminate fatalities caused by roaddeparture, yellow line crossing, stop sign infraction, rear end andexcessive speed accidents. The invention described herein will explainhow these are goals can be attained.

In the IVI Investment Strategy, Critical Technology Elements AndActivities of the DOT, it saves “The IVI will continue to expand theseefforts particularly in areas such as human factors, sensor performance,modeling and driver acceptance”. An alternate, more effective,concentration for investments would be to facilitate the deployment ofthose technologies that will reduce and eventually eliminate highwayfatalities. Driver acceptance and human factors will be discussed below.Too much time and resources have already been devoted to these areas.Modeling can be extremely valuable and sensor performance is in ageneral sense a key to eliminating fatalities.

On Jul. 15, 1998, the IVI light vehicle steering committee met andrecommended that the IVI program should be conducted as a governmentindustry partnership like the PNGV. This is wrong and the IVI should nowmove vigorously toward the deployment of proven technology. The time haspast for endless committee meetings, seminars and planning sessions.

The final recommendations of the committee was “In the next five years,the IVI program should be judged on addressing selected impedimentspreventing deployment, not on the effect of IVI services on accidentrates.” This is a mistake. The emphasis for the next five years shouldbe to deploy proven technologies and to start down the Road to ZeroFatalities™. Five years from now technology should be deployed onproduction vehicles sold to the public that have a significant effecttoward reducing fatalities and injuries.

As described in the paper “Preview Based Control of A Tractor TrailerUsing DGPS For Preventing Road Departure Accidents” the basis of thetechnology proposed has been demonstrated.

REVIEW OF RELEVANT PRIOR ART

The complete disclosure of the following patents is incorporated byreference herein in their entirety. Also, the systems disclosed in thepatents may be used in the invention in appropriate part.

a. Vehicle Collision Warning and Control

The ALVINN project of Carnegie Mellon University describes an autonomousland vehicle using a neural network. The neural network is trained basedon how a driver drives the vehicle given the output from a video camera.The output of the neural network is the direction that the vehicleshould head based on the input information from the video camera and thetraining based on what a good driver would do. Such a system can be usedin the present invention to guide a vehicle to a safe stop in the eventthat the driver becomes incapacitated or some other emergency situationoccurs wherein the driver is unable to control the vehicle. The input tothe neural network in this case would be the map information rather thana video camera. Additionally, the laser radar imaging system of thisinvention could also be an input to the system. This neural networksystem can additionally take over in the event that an accident becomesinevitable. Simple neural networks are probably not sufficient for thispurpose and neural fuzzy and modular neural networks are probablyrequired.

U.S. Pat. No. 5,479,173 to Yoshioka, et al. uses a steering anglesensor, a yaw rate sensor and a velocity of the vehicle sensor topredict the path that the vehicle will take. It uses a radar unit toidentify various obstacles that may be in the path of the vehicle, andit uses a CCD camera to try to determine that the road is changingdirection in front of the vehicle. No mention is made of the accuracywith which these determinations are made. It is unlikely that sub-meteraccuracy is achieved. If an obstacle is sensed the brakes can beautomatically activated.

U.S. Pat, No. 5,540,298 to Yoshioka, et al. is primarily concerned withchanging the suspension and steering characteristics of the vehicle inorder to prevent unstable behavior of the vehicle in response to theneed to exercise a collision avoidance maneuver. The collisionanticipation system consists of an ultrasonic unit and two optical laserradar units.

U.S. Pat. No. 5,572,428 to Ishida is concerned with using a radar systemplus a yaw rate sensor and a velocity sensor to determine whether avehicle will collide with another vehicle based on the area occupied byeach vehicle. Naturally, since radar cannot accurately determine thisarea it has to be assumed by the system.

U.S. Pat. No. 5,613,039 to Wang, et al. is a collision warning radarsystem utilizing a real time adaptive probabilistic neural network. Wangdiscloses that 60% of roadway collisions could be avoided if theoperator of the vehicle was provided warning at least one-half secondprior to a collision. The radar system used by Wang consists of twoseparate frequencies. The reflective radar signals are analyzed by aprobabilistic neural network that provides an output signal indicativeof the likelihood and threat of a collision with a particular object.The invention further includes a Fourier transform circuit that convertsthe digitized reflective signal from a time series to a frequencyrepresentation. It is important to note that in this case, as in theothers above, true collision avoidance will not occur since, without aknowledge of the roadway, two vehicles can be approaching each other ona collision course, each following a curved lane on a highway and yetthe risk of collision is minimal due to the fact that each vehicleremains in its lane. Thus, true collision avoidance cannot be obtainedwithout an accurate knowledge of the road geometry.

U.S. Pat. No. 5,983,161 to Lemelson describes a GPS-based collisionavoidance and warning system that contains some of the features of thepresent invention. This patent is primarily concerned with usingcentimeter-accuracy DGPS systems to permit vehicles on a roadway tolearn and communicate their precise locations to other vehicles. In thatmanner, a pending collision can, in some cases, be predicted.

Lemelson does not use an inertial navigation system for controlling thevehicle between GPS updates. Thus, the vehicle can travel a significantdistance before its position can be corrected. This can lead tosignificant errors. Lemelson also does not make use of accurate mapdatabase and thus it is unable to distinguish cases where two cars areon separate lanes but on an apparent collision course. Although variousradar and lidar systems are generally disclosed, the concept of rangegating is not considered. Thus, the Lemelson system is unable to providethe accuracy and reliability required by the Road to Zero Fatalitiessystem described herein.

b. Accurate Navigation

U.S. Pat. No. 5,504,482 to Schreder describes an automobile equippedwith an inertial and satellite navigation system as well as a local areadigitized street map. The main use of this patent is for route guidancein the presence of traffic jams, etc. Schreder describes how informationas to the state of the traffic on a highway can be transmitted andutilized by a properly equipped vehicle to change the route the driverwould take in going to his destination. Schreder does not disclosesub-meter vehicle location accuracy determination, nevertheless, thispatent provides a good picture of the state of the art as can be seenfrom the following quoted paragraphs:

“. . . there exists a wide range of technologies that havedisadvantageously not been applied in a comprehensive integrated mannerto significantly improve route guidance, reduce pollution, improvevehicular control and increase safety associated with the commonautomobile experience. For example, it is known that gyro based inertialnavigation systems have been used to generate three-dimensional positioninformation, including exceedingly accurate acceleration and velocityinformation over a relatively short travel distance, and that GPSsatellite positioning systems can provide three-dimensional vehicularpositioning and epoch timing, with the inertial system being activatedwhen satellite antenna reception is blocked during “drop out” forcontinuous precise positioning. It is also known that digitized terrainmaps can be electronically correlated to current vehicular transientpositions, as have been applied to military styled transports andweapons. For another example, it is also known that digitally encodedinformation is well suited to RF radio transmission within specifictransmission carrier bands, and that automobiles have been adapted toreceived AM radio, FM radio, and cellular telecommunication RFtransmissions. For yet another example, it is further known thatautomobile electronic processing has been adapted to automaticallycontrol braking, steering, suspension and engine operation, for example,anti-lock braking, four-wheel directional steering, dynamic suspensionstiffening during turns and at high speeds, engine governors limitingvehicular speed, and cruise control for maintaining a desired velocity.For still another example, traffic monitors, such as road embeddedmagnetic traffic light sensor loops and road surface traffic flow metershave been used to detect traffic flow conditions. While these sensors,meters, elements, systems and controls have served limited specificpurposes, the prior art has disadvantageously failed to integrate themin a comprehensive fashion to provide a complete dynamic route guidance,dynamic vehicular control, and safety improvement system.”

“Recently, certain experimental integrated vehicular dynamic guidancesystems have been proposed. Motorola has disclosed an IntelligentVehicle Highway System in block diagram form in copyright dated 1993brochure. Delco Electronics has disclosed another Intelligent VehicleHighway System also in block diagram form in Automotive News publishedon Apr. 12, 1993. These systems use compass technology for vehicularpositioning. However, displacement wheel sensors are plagued by tireslippage, tire wear and are relatively inaccurate requiringrecalibration of the current position. Compasses are inexpensive, butsuffer from drifting particularly when driving on a straight road forextended periods. Compasses can sense turns, and the system may then beautomatically recalibrated to the current position based upon sensing aturn and correlating that turn to the nearest turn on a digitized map,but such recalibration, is still prone to errors during excessivedrifts. Moreover, digitized map systems with the compass and wheelsensor positioning methods operate in two dimensions on a threedimensional road terrain injecting further errors between the digitizedmap position and the current vehicular position due to a failure tosense the distance traveled in the vertical dimension.”

“These Intelligent Vehicle Highway Systems appear to use GPS satellitereception to enhance vehicular tracking on digitized road maps as partof a guidance and control system. These systems use GPS to determinewhen drift errors become excessive and to indicate that recalibration isnecessary. However, the GPS reception is not used for automatic accuraterecalibration of current vehicular positioning, even though C-MIGITS andlike devices have been used for GPS positioning, inertial sensing andepoch time monitoring, which can provide accurate continuouspositioning.”

“These Intelligent Vehicle Highway Systems use the compass and wheelsensors for vehicular positioning for route guidance, but do not useaccurate GPS and inertial route navigation and guidance and do not useinertial measuring units for dynamic vehicular control. Even thoughdynamic electronic vehicular control, for example, anti-lock braking,anti-skid steering, and electronic control suspension have beencontemplated by others, these systems do not appear to functionallyintegrate these dynamic controls with an accurate inertial routeguidance system having an inertial measuring unit well suited fordynamic motion sensing. There exists a need to further integrate andimprove these guidance systems with dynamic vehicular control and withimproved navigation in a more comprehensive system.”

“These Intelligent Vehicle Highway Systems also use RF receivers toreceive dynamic road condition information for dynamic route guidance,and contemplate infrastructure traffic monitoring, for example, anetwork for road magnetic sensing loops, and contemplate the RFbroadcasting of dynamic traffic conditions for dynamic route guidance.The disclosed two-way RF communication through the use of a transceiversuggests a dedicated two-way RF radio data system. While two-way RFcommunication is possible, the flow of necessary information between thevehicles and central system appears to be exceedingly lopsided. The flowof information from the vehicles to a central traffic radio data controlsystem may be far less than the required information from traffic radiodata control system to the vehicles. It seems that the amount ofbroadcasted dynamic traffic flow information to the vehicles would befar greater than the information transmitted from the vehicles to thecentral traffic control center. For example, road side incident oraccident emergency, messages to a central system may occur far less thanthe occurrences of congested traffic points on a digitized map having alarge number of road coordinate points.”

“Conserving bandwidth capacity is an objective of RF communicationsystems. The utilization of existing infra structure telecommunicationswould seem cost-effective. AT&T has recently suggested improving theexisting cellular communication network with high-speed digital cellularcommunication capabilities. This would enable the use of cellulartelecommunications for the purpose of transmitting digital informationencoding the location of vehicular incidents and accidents. It thenappears that a vehicular radio data system would be cost-effectivelyused for unidirectional broadcasting of traffic congestion informationto the general traveling public, while using existing cellulartelecommunication systems for transmitting emergency information. Thecommunication system should be adapted for the expected volume ofinformation. The Intelligent Vehicular Highway Systems disadvantageouslysuggest a required two-way RF radio data system. The vast amount ofinformation that can be transmitted may tend to expand and completelyoccupy a dedicated frequency bandwidth. To the extent that any system isbi-directional in operation tends to disadvantageously requireadditional frequency bandwidth capacity and system complexity.”

c. Vehicle Location

Three attempts to improve the position accuracy of GPS are discussedhere, the Wide Area Augmentation System (WAAS), the Local AreaAugmentation System (LAAS) and various systems that make use of thecarrier phase.

A paper by S. Malys et al., titled “The GPS Accuracy ImprovementInitiative” provides a good discussion of the errors inherent in the GPSsystem without using differential corrections. It is there reported thatthe standard GPS provides a 9-meter RMS 3-D navigational accuracy toauthorize precise positioning service users. This reference indicatesthat there are improvements planned in the GPS system that will furtherenhance its accuracy. The accuracies of these satellites independentlyof the accuracies of receiving units is expected to be between 1 and 1.5meters RMS. Over the past eight years of GPS operations, a 50% (4.6meter to 2.3 meter) performance improvement has been observed for thesignal in space range errors. This, of course, is the RMS error. Theenhancements contained in the accuracy improvement initiative willprovide another incremental improvement from the current 2.3 meters to1.3 meters and perhaps to as low as 40 centimeters.

Pullen, Samuel, Enge, Per and Parkinson, Bradford, “Simulation-BasedEvaluation of WAAS Performance: Risk and Integrity Factors” discussesthe accuracy that can be expected from the WAAS system. This paperindicates that the standard deviation for WAAS is approximately 1 meter.To get more accurate results requires more closely spaced differentialstations. Using DGPS stations within 1,500 kilometers from the vehicle,high accuracy receivers can determine a location within 3 metersaccuracy for DGPS according to the paper. Other providers of DGPScorrections claim considerably better accuracies.

From a paper by J. F. Zumberge, M. M. Watkins and F. H. Webb, titled“Characteristics and Applications of Precise GPS Clock Solutions Every30 Seconds”, Journal of the Institute of Navigation, Vol. 44, No. 4,Winter 1997-1998, it appears that using the techniques described in thisreference that the WAAS system could eventually be improved to provideaccuracies in the sub-decimeter range for moving vehicles without theneed for differential other GPS systems. This data would be providedevery 30 seconds.

W. I. Bertiger et al., “A Real-Time Wide Area Differential GPS System”,Journal of the Institute of Navigation, Vol. 44. No. 4, Winter1997-1998. This paper describes the software that is to be used with theWAAS System. The WAAS System is to be completed by 2001. The goal of theresearch described in this paper is to achieve sub-decimeter accuraciesworldwide, effectively equaling local area DGPS performance worldwide.The full computation done on a Windows NT computer adds only about 3milliseconds. The positioning accuracy is approximately 25 centimetersin the horizontal direction. That is the RMS value so that gives anerror at ±3 sigma of 1.5 meters. Thus, this real time wide areadifferential GPS system is not sufficiently accurate for the purposes ofthis invention. Other systems claim higher accuracies.

According to the paper by R. Braff, titled “Description of the FAA'sLocal Area Augmentation System (LAAS)”, Journal of the Institute ofNavigation, Vol. 44, No. 4, Winter 1997-1998, the LAAS System is theFAA's ground-based augmentation system for local area differential GPS.It is based on providing corrections of errors that are common to bothground-based and aircraft receivers. These corrections are transmittedto the user receivers via very high frequency VHF, line of sight radiobroadcast. LAAS has the capability of providing accuracy on the order of1 meter or better on the final approach segment and through rollout.LAAS broadcasts navigational information in a localized service volumewithin approximately 30 nautical miles of the LAAS ground segment.

O'Connor, Michael, Bell, Thomas, Elkaim, Gabriel and Parkinson,Bradford, “Automatic Steering of Farm Vehicles Using GPS” describes anautomatic steering system for farm vehicles where the vehicle lateralposition error never deviated by more than 10 centimeters, using acarrier phase differential GPS system whereby the differential stationwas nearby.

The following quote is from Y. M. Al-Haifi et al., ”PerformanceEvaluation of GPS Single-Epoch On-the Fly Ambiguity Resolution”, Journalof the Institute of Navigation, Vol. 44, No. 4, Winter 1997-1998. Thistechnique demonstrates sub-centimeter precision results all of the timeprovided that at least five satellites are available and multipatherrors are small. A resolution of 0.001 cycles is not at all unusual forgeodetic GPS receivers. This leads to a resolution on the order of 0.2millimeters. In practice, multipath affects, usually from nearbysurfaces, limit the accuracy achievable to around 5 millimeters. It iscurrently the case that the reference receiver can be located within afew kilometers of the mobile receiver. In this case, most of the otherGPS error sources are common. The only major problem, which needs to besolved to carry out high precision kinematic GPS, is the integerambiguity problem. This is because at any given instant the whole numberof cycles between the satellite and the receiver is unknown. Therecovery of the unknown whole wavelengths or integer ambiguities istherefore of great importance to precise phase positioning. Recently, alarge amount of research has focused on so called on the fly (OTF)ambiguity resolution methodologies in which the integer ambiguities aresolved for while the unknown receiver is in motion.

The half-second processing time required for this paper represents 44feet of motion for a vehicle traveling at 60 mph, which would beintolerable unless supplemented by an inertial navigation system. Thebasic guidance system in this case would have to be the laser or MEMSgyro on the vehicle. With a faster PC, one-tenth a second processingtime would be achievable, corresponding to approximately 10 feet ofmotion of the vehicle, putting less reliance on the laser gyroscope.Nowhere in this paper is the use of this system on automobilessuggested. The technique presented in this paper is a single epoch basis(OTF) ambiguity resolution procedure that is insensitive to cycle slips.This system requires the use of five or more satellites which suggeststhat additional GPS satellites may need to be launched to make the smarthighway system more accurate.

F. van Diggelen. “GPS and GPS+GLONASS RTK”, ION-GPS, September 1997 “NewProducts Descriptions”, gives a good background of real time kinematicsystems using the carrier frequency. The products described in thispaper illustrate the availability of centimeter level accuracies for thepurposes of the RtZF system. The product described in F. van Diggelenrequires a base station that is no further than 20 kilometers away.

A paper by J. Wu and S. G. Lin, titled “Kinematic Positioning with GPSCarrier Phases by Two Types of Wide Laning”, Journal of the Institute ofNavigation, Vol. 44, No. 4, Winter 1997 discloses that the solution ofthe integer ambiguity problem can be simplified by performing otherconstructs other than the difference between the two phases. One exampleis to use three times one phase angle, subtracted from four timesanother phase angle. This gives a wavelength of 162.8 centimeters vs.86.2 for the single difference. Preliminary results with a 20-kilometerbase line show a success rate as high as 95% for centimeter levelaccuracies.

A paper by R. C. Hayward et al., titled “Inertially Aided GPS BasedAttitude Heading Reference System (AHRS) for General Aviation Aircraft”provides the list of inertial sensors that can be used with theteachings of this invention.

K. Ghassemi et al., “Performance Projections of GPS IIF”, describes theperformance objectives for a new class of GPS 2F satellites to belaunched in late 2001.

Significant additional improvement can be obtained for the WAAS systemusing the techniques described in the paper “Incorporation of orbitaldynamics to improve wide-area differential GPS” which is included hereinby reference.

Singh, Daljit and Grewal, Harkirat, “Autonomous Vehicle using WADGPS”,discusses ground vehicle automation using wide-area DGPS. Though thisreference describes many of the features of the present invention, itdoes not disclose sub-meter accuracy or sub-meter accurate mapping.

U.S. Pat. No. 5,272,483 to Kato describes an automobile navigationsystem. This invention attempts to correct for the inaccuracies in theGPS system through the use of an inertial guidance, geomagnetic sensor,or vehicle crank shaft speed sensor. However, it is unclear as towhether the second position system is actually more accurate than theGPS system. This combined system, however, cannot be used for sub-meterpositioning of an automobile.

U.S. Pat. No. 5,383,127 to Shibata uses map matching algorithms tocorrect for errors in the GPS navigational system to provide a moreaccurate indication of where the vehicle is or, in particular, on whatroad the vehicle is. This procedure does not give sub-meter accuracy.Its main purpose is for navigation and, in particular, in determiningthe road on which the vehicle is traveling.

U.S. Pat. No. 5,416,712 to Geier, et al. relates generally to navigationsystems and more specifically to global positioning systems that usedead reckoning apparatus to fill in as backup during periods of GPSshadowing such as occur amongst obstacles, e.g., tall buildings in largecities. This patent shows a method of optimally combining theinformation available from GPS even when less than 3 or 4 satellites areavailable with information from a low-cost, inertial gyro, having errorsthat range from 1-5%. This patent provides an excellent analysis of howto use a modified Kalman filter to optimally use the availableinformation.

U.S. Pat. No. 5,606,506 to Kyrtsos provides a good background of the GPSsatellite system. It discloses a method for improving the accuracy ofthe GPS system using an inertial guidance system. This is based on thefact that the GPS signals used by Kyrtsos do not contain a differentialcorrection and the selective access feature is on. Key paragraphs fromthis application that is applicable to the instant invention follow.

“Several national governments, including the United States (U.S.) ofAmerica, are presently developing a terrestrial position determinationsystem, referred to generically as a global positioning system (GPS). AGPS is a satellite-based radio-navigation system that is intended toprovide highly accurate three-dimensional position information toreceivers at or near the surface of the Earth.

“The U.S. government has designated its GPS the “NAVSTAR.” The NAVSTARGPS is expected to be declared fully operational by the U.S. governmentin 1993. The government of the former Union of Soviet SocialistRepublics (USSR) is engaged in the development of a GPS known as“GLONASS”. Further, two European systems known as “NAVSAT” and “GRANAS”are also under development. For ease of discussion, the followingdisclosure focuses specifically on the NAVSTAR GPS. The invention,however, has equal applicability to other global positioning systems.“In the NAVSTAR GPS, it is envisioned that four orbiting GPS satelliteswill exist in each of six separate circular orbits to yield a total oftwenty-four GPS satellites. Of these, twenty-one will be operational andthree will serve as spares. The satellite orbits will be neither polarnor equatorial but will lie in mutually orthogonal inclined planes.”

“Each GPS satellite will orbit the Earth approximately once every 12hours. This coupled with the fact that the Earth rotates on its axisonce every twenty-four hours causes each satellite to complete exactlytwo orbits while the Earth turns one revolution.”

“The position of each satellite at any given time will be preciselyknown and will be continuously transmitted to the Earth. This positioninformation, which indicates the position of the satellite in space withrespect to time (GPS time), is known as ephemeris data.”

“In addition to the ephemeris data, the navigation signal transmitted byeach satellite includes a precise time at which the signal wastransmitted. The distance or range from a receiver to each satellite maybe determined using this time of transmission which is included in eachnavigation signal. By noting the time at which the signal was receivedat the receiver, a propagation time delay can be calculated. This timedelay when multiplied by the speed of propagation of the signal willyield a “pseudorange” from the transmitting satellite to the receiver.”

“The range is called a “pseudorange” because the receiver clock may notbe precisely synchronized to GPS time and because propagation throughthe atmosphere introduces delays into the navigation signal propagationtimes. These result, respectively, in a clock bias (error) and anatmospheric bias (error). Clock biases may be as large as severalmilliseconds.”

“Using these two pieces of information (the ephemeris data and thepseudorange) from at least three satellites, the position of a receiverwith respect to the center of the Earth can be determined using passivetriangulation techniques.”

“Triangulation involves three steps. First, the position of at leastthree satellites in “view” of the receiver must be determined. Second,the distance from the receiver to each satellite must be determined.Finally, the information from the first two steps is used togeometrically determine the position of the receiver with respect to thecenter of the Earth.”

“Triangulation, using at least three of the orbiting GPS satellites,allows the absolute terrestrial position (longitude, latitude, andaltitude with respect to the Earth's center) of any Earth receiver to becomputed via simple geometric theory. The accuracy of the positionestimate depends in part on the number of orbiting GPS satellites thatare sampled. Using more GPS satellites in the computation can increasethe accuracy of the terrestrial position estimate.”

“Conventionally, four GPS satellites are sampled to determine eachterrestrial position estimate. Three of the satellites are used fortriangulation, and a fourth is added to correct for the clock biasdescribed above. If the receiver's clock were precisely synchronizedwith that of the GPS satellites, then this fourth satellite would not benecessary. However, precise (e.g., atomic) clocks are expensive and are,therefore, not suitable for all applications.”

“For a more detailed discussion on the NAVSTAR GPS, see Parkinson,Bradford W. and Gilbert, Stephen W., “NAVSTAR: Global PositioningSystem—Ten Years Later, “Proceedings of the WEEE, Vol. 71, No. 10,October 1983; and GPS: A Guide to the Next Utility, published by TrimbleNavigation Ltd., Sunnyvale, Calif., 1989, pp. 147, both of which areincorporated herein by reference. For a detailed discussion of a vehiclepositioning/navigation system which uses the NAVSTAR GPS, see commonlyowned U.S. patent application Ser. No. 07/628,560, entitled “VehiclePosition Determination System and Method,” filed Dec. 3, 1990, which isincorporated herein by reference.”

“The NAVSTAR GPS envisions two modes of modulation for the carrier waveusing pseudorandom signals. In the first mode, the carrier is modulatedby a “C/A signal” and is referred to as the “Coarse/Acquisition mode”.The Coarse/Acquisition or C/A mode is also known as the “StandardPositioning Service”. The second mode of modulation in the NAVSTAR GPSis commonly referred to as the “precise” or “protected” (P) mode. TheP-mode is also known as the “Precise Positioning Service”.

The P-mode is intended for use only by Earth receivers specificallyauthorized by the United States government. Therefore, the P-modesequences are held in secrecy and are not made publicly available. Thisforces most GPS users to rely solely on the data provided via the C/Amode of modulation (which results in a less accurate positioningsystem).

“Moreover, the U.S. government (the operator of the NAVSTAR GPS) may atcertain times introduce errors into the C/A mode GPS data beingtransmitted from the GPS satellites by changing clock and/or ephemerisparameters. That is, the U.S. government can selectively corrupt the GPSdata. The ephemeris and/or the clock parameters for one or moresatellites may be slightly or substantially modified. This is known as“selective availability” or simply SA. SA may be activated for a varietyof reasons, such as national security.”

“When SA is activated, the U.S. government is still able to use theNAVSTAR GPS because the U.S. government has access to the P-modemodulation codes. The C/A mode data, however, may be renderedsubstantially less accurate.”

“In addition to the clock error, the atmospheric error and errors fromselective availability, other errors which affect GPS positioncomputations include receiver noise, signal reflections, shading, andsatellite path shifting (e.g., satellite wobble). These errors result incomputation of incorrect pseudoranges and incorrect satellite positions.Incorrect pseudoranges and incorrect satellite positions, in turn, leadto a reduction in the precision of the position estimates computed by avehicle positioning system.”

Note, the selective access has now been permanently turned off by theU.S. Government but may be reintroduced during periods of nationalemergency.

U.S. Pat. No. 5,757,646 to Talbot, et al. illustrates the manner inwhich centimeter level accuracy on the fly in real time is obtained. Itis accomplished by double differencing the code and carrier measurementsfrom a pair of fixed and roving GPS receivers. This patent also presentsan excellent discussion of the problem and of various prior solutions asin the following paragraphs:

“When originally conceived, the global positioning system (GPS) that wasmade operational by the United States Government was not foreseen asbeing able to provide centimeter-level position accuracies. Suchaccuracies are now conmmonplace.”

“Extremely accurate GPS receivers depend on phase measurements of theradio carriers that they receive from various orbiting GPS satellites.Less accurate GPS receivers simply develop the pseudoranges to eachvisible satellite based on the time codes being sent. Within thegranularity of a single time code, the carrier phase can be measured andused to compute range distance as a multiple of the fundamental carrierwavelength. GPS signal transmissions are on two synchronous, butseparate carrier frequencies “L1” and “L2”, with wavelengths of nineteenand twenty-four centimeters, respectively. Thus within nineteen ortwenty-four centimeters, the phase of the GPS carrier signal will change360°.”

“However the numbers of whole cycle (360°) carrier phase shifts betweena particular GPS satellite and the GPS receiver must be resolved. At thereceiver, every cycle will appear the same. Therefore there is an“integer ambiguity”. The computational resolution of the integerambiguity has traditionally been an intensive arithmetic problem for thecomputers used to implement GPS receivers. The traditional approaches tosuch integer ambiguity resolution have prevented on-the-fly solutionmeasurement updates for moving GPS receivers with centimeter accurateoutputs. Very often such highly accurate GPS receivers have requiredlong periods of motionlessness to produce a first and subsequentposition fix.”

“There are numerous prior art methods for resolving integer ambiguities.These include integer searches, multiple antennas, multiple GPSobservables, motion-based approaches, and external aiding. Searchtechniques often require significant computation time and are vulnerableto erroneous solutions when only a few satellites are visible. Moreantennas can improve reliability considerably. If carried to an extreme,a phased array of antennas results whereby the integers are completelyunambiguous and searching is unnecessary. But for economy the minimumnumber of antennas required to quickly and unambiguously resolve theintegers, even in the presence of noise, is preferred.”

“One method for integer resolution is to make use of the otherobservables that modulate a GPS timer. The pseudo-random code can beused as a coarse indicator of differential range, although it is verysusceptible to multipath problems. Differentiating the L1 and L2carriers provides a longer effective wavelength, and reduces the searchspace. However dual frequency receivers are expensive because they aremore complicated. Motion-based integer resolution methods make use ofadditional information provided by platform or satellite motion. Butsuch motion may not always be present when it is needed.”

This system is used in an industrial environment where the four antennasare relatively close to each other. Practicing the teachings of thisinvention permits a navigational computer to solve for the position ofthe rover to within a few centimeters on the fly ten times a second. Anexample is given where the rover is an airplane.

The above comments related to the use of multiple antennas to eliminatethe integer ambiguity suggest that if a number of vehicles are nearbyand their relative positions are known, that the ambiguity can beresolved.

d. Mapping

It is intended that the map database of the instant invention willconform to the open GIS specification. This will permit such devices toadditionally obtain on-line consumer information services such asdriving advisories, digital yellow pages that give directions, localweather pictures and forecasts and video displays of local terrain sincesuch information will also be in the GIS database format.

A paper by O'Shea, Michael and Shuman, Valerie entitled “Looking Ahead:Map Databases in Predictive Positioning And Safety Systems” discussesmap databases which can assist radar and image-processing systems ofthis invention since the equipped vehicle would know where the roadahead is and can therefore distinguish the lane of the precedingvehicle. No mention, however, is made in this reference of how this isaccomplished through range gating or other means. This reference alsomentions that within five years it may be possible to provide real timevehicle location information of one-meter accuracy. However, it mentionsthat this will be limited to controlled access roads such as interstatehighways. In other words, the general use of this information on allkinds of roads for safety purposes is not contemplated. This referencealso states that “road geometry, for example, may have to be accurate towithin one meter or less as compared to the best available accuracy of15 meters today”. This reference also mentions the information aboutlane configuration that can be part of the database including the widthof each lane, the number of lanes, etc., and that this can be used todetermine driver drowsiness. This reference also states that “at normalvehicle speeds, the vehicle location must be updated every fewmilliseconds. It is also stated that the combination of radar and mapdata can also help to interpret radar information such as the situationwhere a radar system describes an overpass as a semi truck . . . ” Imageprocessing in this reference is limited to assessing road conditionssuch as rain, snow, etc. The use of a laser radar system is notcontemplated by this reference. The use of this information for roaddepartures warnings is also mentioned, as is lane following. Thereference also mentions that feedback from vehicles can be used toimprove map configurations.

A great flow of commercially available data will begin with the newgeneration of high resolution (as fine as about 1 meter) commercialearth imaging satellites from companies like EarthWatch and SPOT Image.Sophisticated imaging software is being put in place to automaticallyprocess these imaging streams into useful data products. This data canbe used to check for gross errors in the map database.

According to Al Gore, in “The Digital Earth: Understanding our Planet inthe 21^(st) Century”, California Science Center, Jan. 31, 1998, theClinton Administration licensed commercial satellites to provide onemeter resolution imaging beginning in 1998. Such imaging can be combinedwith digital highway maps to provide an accuracy and reality check.

U.S. Pat. No. 5,367,463 to Tsuji describes a vehicle azimuth determiningsystem. It uses regression lines to find the vehicle on a map when thereare errors in the GPS and map data. This patent does not give sub-meteraccuracy. The advantage of this invention is that it shows a method ofcombining both map matching data and GPS along with a gyro and a vehiclevelocity and odometer data to improve the overall location accuracy ofthe vehicle.

e. Speed Control

U.S. Pat. No. 5,530,651 to Uemura, et al. discloses a combination of anultrasonic and laser radar optical detection system which has theability to detect soiled lenses, rain, snow, etc. The vehicle controlsystem then automatically limits the speed, for example, that thevehicle can travel in adverse weather conditions. The speed of thevehicle is also reduced when the visibility ahead is reduced due to ablind, curved corner. The permitted speed is thus controlled based onweather conditions and road geometry. There is no information in thevehicle system as to the legal speed limit as provided for in theinstant invention.

f. Precise Positioning

When the operator begins operating his vehicle with a version of theRtZF system of this invention, he or she will probably not be near areference point as determined by the MIR or RFID locator system, forexample. In this situation, he or she will use the standard GPS systemwith the WAAS or other DGPS corrections. This will provide accuracy ofbetween a few meters to 6 centimeters. This accuracy might be furtherimproved as he or she travels down the road through map-matching orthrough communication with other vehicles. The vehicle will know,however, that is not operating in the high accuracy mode. As soon as thevehicle passes an MRI, RFID or equivalent precise positioning system, itwill be able to calculate exactly where it is within a few centimetersand the vehicle will know that it is in the accurate mode. Naturally,any travel on a controlled highway would require frequent MIR, RFID orequivalent stations and the vehicle can be accurately contained withinits proper corridors. Also, the size of the corridors that the vehicleis permitted to travel in can be a function of the accuracy state of thevehicle.

A paper by Han, Shaowei entitled “Ambiguity Recovery For Long-Range GPSKinematic Positioning” appears to say that if a mobile receiver isinitially synchronized with a fixed receiver such that there is nointeger ambiguity, and if the mobile receiver then travels away from thefixed receiver, and during the process it loses contact with thesatellites for a period of up to five minutes, that the carrier phasecan be recovered and the ambiguity eliminated, providing againcentimeter-range accuracies. Presumably the fixed station is providingthe differential corrections. This is important for the instantinvention since the integer ambiguity can be eliminated each time thevehicle passes a precise positioning station such as the MIR or RFIDtriad or equivalent as explained below. After that, a five-minute lossof GPS signals should never occur. Thus, carrier phase accuracies willeventually be available to all vehicles.

This concept can be further expanded upon. If two vehicles are travelingnear each other and have established communication, and assuming thateach vehicle can observe at least four of the same GPS satellites, eachvehicle can send the satellite identification and the time of arrival ofthe signal at a particular epoch to the other. Then each vehicle candetermine the relative position of the other vehicle as well as therelative clock error. As one vehicle passes a Precise PositioningStation (PPS), it knows exactly where it is and thus the second vehiclealso knows exactly where it is and can correct for satellite errors. Allvehicles that are in communication with the vehicle at the PPS similarlycan determine their exact position and the system again approachesperfection. This concept is based on the fact that the errors in thesatellite signals are identical for all vehicles that are within a mileor so of each other.

U.S. Pat. No. 5,361,070 to McEwan, although describing a motiondetector, discloses technology which is used as part of a system topermit a vehicle to precisely know where it is on the face of the earthat particular locations. The ultra wideband 200 picosecond radar pulseemitted by the low power radar device of McEwan is inherently a spreadspectrum pulse which generally spans hundreds of megahertz to severalgigahertz. A frequency allocation by the FCC is not relevant.Furthermore, many of these devices may be co-located withoutinterference. The concept of this device is actually disclosed invarious forms in the following related patents to McEwan. The followingcomments will apply to these patents as a group, all of which areincorporated herein by reference.

U.S. Pat. No. 5,510,802 to McEwan describes a time of flightradio-location system similar to what is described below. In this case,however, a single transmitter sends out a pulse, which is received bythree receivers to provide sub-millimeter resolution. The range of thisdevice is less than about 10 feet.

The concept described in McEwan's U.S. Pat. No. 5,519,400 is that theMIR signal can be modulated with a coded sequence to permit positiveidentification of the sending device. In an additional McEwan patent,U.S. Pat. No. 5,589,838, .a short-range radio-location system isdescribed. Additionally, in U.S. Pat. No. 5,774,091, McEwan claims thatthe MIR system will operate to about 20 feet and give resolutions on theorder of 0.01 inches.

g. Radar and Laser Radar Detection and Identification of ObjectsExternal to the Vehicle

A paper by Amamoto, Naohiro and Matsumoto, Koji entitled “ObstructionDetector By Environmental Adaptive Background Image Updating” describesa method for distinguishing between moving object pixels, stationaryobject pixels, and pixels that change due to illumination changes in avideo image. This paper appears to handle the case of a camera fixedrelative to the earth, not one mounted on a vehicle. This allows thesystem to distinguish between a congested area and an area where carsare moving freely. The video sampling rate was 100 milliseconds.

A paper by Doi, Ayumu, Yamamomo; Yasunori,and Butsuen, Tetsuro entitled“Development Of Collision Warning System and Its Collision AvoidanceEffect” describes a collision warning system that has twice the accuracyof conventional systems. It uses scanning laser radar. In the systemdescribed in this paper, the authors do not appear to use range gatingto separate one vehicle from another.

A paper by Min, Joon, Cho. Hyung, and Choi, Jong, entitled “A LearningAlgorithm Using Parallel Neuron Model” describes a method of accuratelycategorizing vehicles based on the loop in the highway. This system usesa form of neural network, but not a back propagation neural network.This would essentially be categorizing a vehicle by its magneticsignature. Much information is lost in this system, however, due to thelack of knowledge of the vehicle's velocity.

Another paper describes work done at JPL (Jet Propulsion Laboratories)to develop a target recognition system. In this paper, neural networkspay a key role in that target recognition process. The recognition ofvehicles on a roadway is a considerably simpler process. Although notdisclosed in this paper, most of the cluttering information can beeliminated through range gating. The three-dimensional image obtained asdescribed below will permit simple rotations of the image toartificially create a frontal view of the object being investigated.Also, the targets of interest here are considerably closer than wasconsidered by JPL. Nevertheless, the techniques described in thisreference and in the references cited by this reference, all of whichare included herein by reference, are applicable here in a simplifiedform. The JPL study achieved over a 90% success rate at 60 frames perminute.

U.S. Pat. No. 4,521,861 to Logan describes a method and apparatus forenhancing radiometric imaging and a method and apparatus for enhancingtarget detection through the utilization of an imaging radiometer. Theradiometer, which is a passive thermal receiver, detects the reflectedand emitted thermal radiation of targets. Prior to illumination, foliagewill appear hot due to its high emissivity and metals will appear colddue to their low emissivities. When the target is momentarilyilluminated foliage appears dark while metals appear hot. By subtractingthe non-illuminated image from the illuminated image, metal targets areenhanced. The teachings of this patent thus have applicability to theinstant invention as discussed below.

U.S. Pat. No. 5,463,384 to Juds uses a plurality of infrared beams toalert a truck driver that a vehicle is in his blind spot when he beginsto turn the vehicle. The system is typically activated by the vehicle'sturn signal. No attempt is made to measure exactly where the object is,only whether it is in the blind spot or not.

U.S. Pat. No. 5,467,072 to Michael relates to a phased array radarsystem that permits the steering of a radar beam without having torotate antennas. Aside from that, it suffers from all the disadvantagesof radar systems as described here. In particular, it is not capable ofgiving accurate three-dimensional measurements of an object on theroadway.

U.S. Pat. No. 5,486,832 to Hulderman employs millimeter wave radar andoptical techniques to eliminate the need for a mechanical scanningsystem. A 35-degree are is illuminated in the azimuth direction and 6degrees in elevation. The reflected waves are separated into sixteenindependent, simultaneously overlapping 1.8 degree beams. Each beam,therefore, covers a width of about 3 feet at 100 feet distance from thevehicle, which is far too large to form an image of the object in thefield of view. As a result, it is not possible to identify the objectsin the field of view. All that is known is that an object exists. Also,no attempt has been made to determine whether the object is located onthe roadway or not. Therefore, this invention suffers from thelimitations of other radar systems.

U.S. Pat. No. 5,530,447 to Henderson, et al. shows a system used toclassify targets as threatening or non-threatening, depending on whetherthe target is moving relative to the ground. This system is only forvehicles in an adjacent lane and is primarily meant to protect againstblind-spot type accidents. No estimation is made by the system of theposition of the target vehicle or the threatening vehicle, only itsrelative velocity.

U.S. Pat. No. 5.576,972 to Harrison provides a good background of howneural networks are used to identify various of objects. Although notdirectly related to intelligent transportation systems or toaccident-avoidance systems such as described herein, these techniqueswill be applied to the invention described herein as discussed below.

U.S. Pat. No. 5.585.798 to Yoshioka. et al. uses a combination of a CCDcamera and a laser radar unit. The invention attempts to make a judgmentas to the danger of each of the many obstacles that are detected. Theload on the central processor is monitored by looking at differentobstacles with different frequencies depending on their danger to thepresent system. A similar arrangement is contemplated for the inventionas disclosed herein.

U.S. Pat. No. 5,767,953 to McEwan describes a laser tape measure formeasuring distance. It is distinct from laser radars in that the widthof the pulse is measured in sub-nanosecond times, whereas laser radarsare typically in the microsecond range. The use of this technology inthe current invention would permit a much higher scanning rate than byconvention radar systems and thus provide the opportunity for obtainingan image of the obstructions on the highway. It is also less likely thatmultiple vehicles having the same system would interfere with eachother. For example, if an area 20 feet by 5 feet were scanned with a 0.2inch pixel size, this would give about one million pixels. If usinglaser radar, one pixel per microsecond is sent out, it would take onesecond to scan the entire area during which time the vehicle hastraveled 88 feet at 60 miles an hour. On the other hand, if scanningthis array at 100 feet, it would take 200 nanoseconds for the light totravel to the obstacle and back. Therefore, if a pulse is sent out everyfifth of a microsecond, it will take a fifth of a second to obtain amillion pixels, during which time the vehicle has traveled about 17feet. If 250,000 pixels are used, the vehicle will only have traveledabout 4 feet.

U.S. Pat. Nos. 4,352,105 and 4,298,280 to Harney describe an infraredradar system and a display system for use by aircraft. In particular,these patents describe an infrared radar system that provides highresolution, bad whether penetration, day-night operation and which canprovide simultaneous range, intensity and high resolution angularinformation. The technology uses CO₂ laser and a 10.6 micron heterodynedetection. It is a compact imaging infrared radar system that can beused with the invention described herein. Harney applies this technologyto aircraft and does not contemplate its application to collisionavoidance or for other uses with automobiles.

h. Smart Highways

A paper entitled “Precursor Systems Analyses of Automated HighwaySystems (Executive Summary)” discloses that “an AHS (automated highwaysystem) can double or triple the efficiency of today's most congestedlanes while significantly increasing safety and trip quality”.

There are one million, sixty-nine thousand, twenty-two miles of pavednon-local roads in the US. Eight hundred twenty-one thousand and fourmiles of these are classified as “rural” and the remaining two hundredforty-eight thousand, eighteen miles are “urban”.

The existing interstate freeway system consists of approximately 50,000miles which is 1% of the total of 3.8 million miles of roads. Freewaysmake up 3% of the total urban/suburban arterial mileage and carryapproximately 30% of the total traffic.

In one study, dynamic route guidance systems were targeting at reducingtravel time of the users by 4%. Under the system of this invention, thetravel times would all be known and independent of congestion once avehicle had entered the system. Under the current system, the dynamicdelays can change measurably after a vehicle is committed to a specificroute. According to the Federal Highway Administration IntelligentTransportation Systems (ITS Field Operational Test), dynamic routeguidance systems have not been successful.

There are several systems presented in the Federal HighwayAdministration Intelligent Transportation Systems (ITS Field OperationalTest) for giving traffic information to commuters, called “AdvanceTraveler Information System” (ATIS). In none of these articles does itdiscuss the variation in travel time during rush hour for example, fromone day to the next. The variability in this travel time would have tobe significant to justify such a system. Naturally, a system of thistype would be unnecessary in situations where the instant invention hasbeen deployed. The single most important cause of variability from dayto day is traffic incidents such as accidents, which are eliminated orat least substantially reduced by the instant invention. One of theconclusions in a study published in the “Federal Highway AdministrationIntelligent Transportation Systems (ITS Field Operational Test)”entitled “Direct Information Radio Using Experimental CommunicationTechnologies” was that drivers did not feel that the system was asignificant advance over commercial radio traffic information. They didthink the system was an improvement over television traffic informationand changeable message signs. The drivers surveyed on average havingchanged their route only one time in the eight week test period due toinformation they received from the system.

i. Weather and Road Condition Monitoring

A paper by Miyata, Yasuhiro and Otomo, Katsuya, Kato, Haijime, Imacho,Nobuhiro, Murata, Shigeo, entitled “Development of Road Icing PredictionSystem” describes a method of predicting road icing conditions severalhours in advance based on an optical fiber sensor laid underneath theroad and the weather forecast data of that area.

There is likely a better way of determining ice on the road thandescribed in this paper. The reflection of an infrared wave off the roadvaries significantly depending on whether there is ice on the road orsnow, or the road is wet or dry. An unsupervised neural network could bea better solution. The system of this paper measures the road surfacetemperature, air temperature and solar radiation. A combination ofactive and passive infrared would probably be sufficient. Perhaps, aspecially designed reflective surface could be used on the road surfacein an area where it is not going to be affected by traffic.

What this paper shows is that if the proper algorithm is used, theactual road temperature can be predicted without the need to measure theroad surface temperature. This implies that icing conditions can bepredicted and the sensors would not be necessary. Perhaps, a neuralnetwork algorithm that monitors a particular section of road andcompares it to the forecasted data would be all that is required. Inother words, given certain meteorological data, the neural network oughtto be able to determine the probability of icing. What is needed,therefore, is to pick a section of roadway and monitor that roadway witha state-owned vehicle throughout the time period when icing is likely tooccur and determine if icing has occurred and compare that with themeteorological data using a neural network that is adapted for eachsection of road.

j. Vehicle to Vehicle Communication

U.S. Pat. No. 5,506,584 to Boles relates to a system for communicationbetween vehicles through a transmit and transponder relationship. Thepatent mentions that there may be as many as 90 vehicles within one halfmile of an interrogation device in a multi-lane environment, where manyof them may be at the same or nearly the same range. Boles utilizes atransponder device, the coded responses which are randomized in time,and an interrogation device which processes the return signals toprovide vehicle identification speed, location and transponder statusinformation on vehicles to an operator or for storage in memory. Nomention is made of how a vehicle knows its location or how accurate thatknowledge is and therefore how it can transmit that location to othervehicles.

k. Infrastructure to Vehicle Communication

The DGPS correction information can be broadcast over the radio datasystem (RDS) via FM transmitters for land use. A company calledDifferential Correction, Inc. has come up with a technique to transmitthis DGPS information on the RDS channel. This technique has been usedin Europe since 1994 and, in particular, Sweden has launched anationwide DPGS service via the RDS (see, Sjoberg, Lars, “A ‘1 Meter’Satellite Based Navigation Solutions for the Mobile Environment ThatAlready Are Available Throughout Europe”). This system has the potentialof providing accuracies on the premium service of between about 1 and 2meters. A 1 meter accuracy, coupled with the carrier phase system to bedescribed below, provides an accuracy substantially better than about 1meter as preferred in the Road to Zero Fatalities (RtZF) system of thisinvention.

In addition to the FM RDS system, the following other systems can beused to broadcast DGPS correction data: cellular mobile phones,satellite mobile phones, MCA (multi-channel access), wirelesstele-terminals, DARCs/RBDS (radio data systems/radio broadcast datasystem), type FM sub-carrier, exclusive wireless, and pagers. Inparticular, DARC type is used for vehicle information and communicationsystems so that its hardware can be shared. Alternately, the cellularphone system, coupled with the Internet, could be used for transmittingcorrections (see, Ito, Toru and Nishiguchi, Hiroshi entitled“Development of DGPS using FM Sub-Carrier For ITS”) with the exceptionof the Internet comment.

One approach for the cellular system is to use the GSM mobile telephonesystem, which is the Europe-wide standard. This can be used fortransmitting DGPS and possibly map update information (see, Hob, A.,Ilg, J. and Hampel, A. entitled “Integration Potential Of TrafficTelematics).

In Choi, Jong and Kim, Hoi, “An Interim Report: Building A WirelessInternet-Based Traveler's Information System As A Replacement Of CarNavigation Systems”, a system of showing congestion at intersections isbroadcast to the vehicle through the Internet. The use of satellites isdisclosed as well as VCS system.

This is another example of the use of the Internet to provide highwayusers with up-to-date traffic congestion information. Nowhere in thisexample, however, is the Internet used to transmit map information.

A paper by Sheu, Dennis, Liaw, Jeff and Oshizawa, Al, entitled “ACommunication System For In-Vehicle Navigation System” provides anotherdescription of the use of the Internet for real traffic information.However, the author (unnecessarily) complicates matters by using pushtechnology which isn't absolutely necessary and with the belief that theInternet connection to a particular vehicle to allow all vehicles tocommunicate, would have to be stopped which, of course, is not the case.For example, consider the ghome network where everyone on the network isconnected all the time.

A paper by, Rick Schuman entitled “Progress Towards ImplementingInteroperable DSRC Systems In North America” describes the standards fordedicated short-range communications (DSRC). DSRC could be used forinter-vehicle communications, however, its range according to the ITSproposal to the Federal Government would be limited to about 90 meters.Also, there may be a problem with interference from toll collectionsystems, etc. According to this reference, however, “it is likely thatany widespread deployment of intersection collision avoidance orautomated highways would utilize DSRC”. Ultra wide band communicationsystems, on the other hand, are a viable alternative to DSRC asexplained below. The DSRC physical layer uses microwaves in the 902 to928 megahertz band. However, ITS America submitted a petition to the FCCseeking to use the 5.85 to 5.925 gigahertz band for DSRC applications.

A version of CDPD, which is a commercially available mobile, wirelessdata network operated in the packet-switching mode, extends Internetprotocol capabilities to cellular channels. This is reported on in apaper entitled “Intelligent Transportation Systems (ITS) Opportunity”.

According to a paper by Kelly, Robert, Povich, Doublas and Poole,Katherine entitled “Petition of Intelligent Transportation Society ofAmerica for Amendment Of The Commission's Rules to Add IntelligentTransportation Services (ITS) As A New Mobile Service With Co-PrimaryStatus In The 5.850 to 5.925 GHz”, from 1989 to 1993 police received anannual average of over 6.25 million vehicle accident reports. Duringthis same period, the total comprehensive cost to the nation of motorvehicle accidents exceeded the annual average of 400 billion dollars. In1987 alone, Americans lost over 2 billion hours (approximately 22,800years) sitting in traffic jams. Each driver in Washington D.C. wastes anaverage of 70 hours per year idling in traffic. From 1986 to 1996, cartravel has increased almost 40% which amounts to about a 3.4% increaseper year.

Further, from Kelly et al., the FCC has allocated in Docket 94-124, 46.7to 46.9 GHz and 76 to 77 GHz bands for unlicensed vehicular collisionavoidance radar. The petition for DSRC calls for a range of up to about50 meters. This would not be sufficient for the RtZF system. Forexample, in the case of a car passing another car at 150 kilometers perhour. Fifty meters amounts to about one second, which would beinsufficient time for the passing vehicle to complete the passing andreturn to the safe lane. Something more in the order of about 500 meterswould be more appropriate. This, however, may interfere with other usesof DSRC such as automatic toll taking, etc., thus DSRC may not be theoptimum communication system for communication between vehicles. DSRC isexpected to operate at a data rate of approximately 600 kbps. DSRC isexpected to use channels that are six megahertz wide. It might bepossible to allocate one or more of the six megahertz channels to RtZF.

On DSRC Executive Roundtable—Meeting Summary, Appendix I—ProposedChanges to FCC Regulations covering the proposed changes to the FCCregulations, it is stated that “. . . DSRCS systems utilize non-voiceradio techniques to transfer data over short distances between roadsideand mobile units, between mobile units and between portable and mobileunits to perform operations related to the improvement of traffic flow,traffic safety and other intelligent transportation service applications. . . ”, etc.

l. Transponders

Consider placing a requirement that all vehicles have passivetransponders such as RFID tags. This could be part of the registrationsystem for the vehicle and, in fact, could even be part of the licenseplate. This is somewhat disclosed in a paper by Shladover, Stevenentitled “Cooperative Advanced Vehicle Control and Safety Systems(AVCSS)”. AVCSS sensors will make it easy to detect the presence,location and identity of all other vehicles in their vicinity. Passiveradio frequency transponders are disclosed. The use of differential GPSwith accuracies as good as about two (2) centimeters, coupled with aninertial guidance system, is disclosed, as is the ability of vehicles tocommunicate their locations to other vehicles. It discloses the use ofaccurate maps, but not of lateral vehicle control using these maps. Itis obvious from reading this paper that the author did not contemplatethe safety system aspects of using accurate maps and accurate GPS. Infact, the author stresses the importance of cooperation between variousgovernment levels and agencies and the private sector in order to makeAVCSS feasible. “Automotive suppliers cannot sellinfrastructure-dependent systems to their customers until the very largemajority of the infrastructure is suitable equipped.”

m. Intelligent Transportation Infrastructure Benefits

A paper entitled “Intelligent Transportation Infrastructure Benefits:Expected and Experienced” provides a summary of costs and benefitsassociated with very modest ITS implementations. Although a completecost benefit analysis has not been conducted on the instant invention,it is evident from reading this paper that the benefits to costreference will be a very large number.

According to this paper, the congestion in the United States isincreasing at about 9% per year. In 50 metropolitan areas, the cost in1992 was estimated at 48 billion dollars and in Washington, DC itrepresented an annual cost of $822 per person, or $1,580 per registeredvehicle. In 1993, there were 40,115 people killed and 3 million injuredin traffic accidents. Sixty-one percent (61%) of all fatal accidentsoccurred in rural areas. This reference lists the 29 user services thatmake up the ITS program. It is interesting that the instant inventionprovides 24 of the 29 listed user services. A listing of the servicesand their proposed implementation with the RtZF system is:

IVI Services

In the tables below, L=Light Vehicle, H=Heavy Truck, T=Transit,S=Specialty Vehicle.

(1) Rear-End Collision Avoidance Gen. 0 Gen. I Gen. II (1a) Monitorsmotion and location of other LHTS vehicles and other objects in front ofvehicle. (1b) Advises the driver of imminent rear-end LHTS crashes. (1c)Provides automatic braking. LHTS

This service is available now with adaptive cruise control supplied byAutoliv, TRW and other companies.

(2) Road-Departure Collision Avoidance Gen. 0 Gen. I Gen. II (2a)Monitors lane position of the vehicle LHTS and motion relative to edgeof road. (2b) Monitors vehicle speed relative to road LHTS geometry androad conditions. (2c) Advises the driver of imminent LHTS unintentionalroad departure. (2d) Provides cooperative communication LHTS withhighway infrastructure to automatically provide safe speeds for upcomingroad geometry and conditions.

A virtual rumble strip noise will be used to warn the driver.

Gen. 0 Gen. I Gen. II (3) Lane-Change and Merge Collision Avoidance (3a)Monitors lane position of the vehicle. LHTS (3b) Monitors the relativespeed and lane po- LHTS sition of vehicles (including motorcycles)beside and to the rear of the vehicle. (3c) Advises the driver duringthe decision LHTS phase (turn signal activated) of a lane-changemaneuver of the potential for a collision. (3d) Advises the driverduring the action LHTS phase (steering input) of a lane-change maneuverof an imminent collision. (3e) Advises the driver during the action LHTSphase (steering input) of an entry or exit maneuver of an imminentcollision. (4) Intersection Collision Avoidance (4a) Monitors vehicleposition relative to LHTS intersection geometry. (4b) Monitors relativespeed and position of LHTS other vehicles. (4c) Advises the driver ofappropriate action LHTS to avoid a violation of right-of-way at theintersection. (4d) Advises the driver of appropriate action LHTS toavoid an impending collision at the intersection. (4e) Determines theintent of other vehicles LHTS in the intersection to turn, slow down,stop, or violate the right-of-way. (5) Railroad Crossing CollisionAvoidance (5a) Monitors vehicle position relative to LHTS railroadcrossing. (5b) Monitors vehicle position and speed LHTS relative toposition and speed of a train (5c) Advises the driver of appropriateaction LHTS to avoid an impending collision at railroad crossing. (6)Vision Enhancement (6a) Provides an enhanced view of pedes- LHTS triansand roadside features with an infrared system. (6b) Provides an enhancedview of the NA environment using a UV system. (7) Location-SpecificAlert and Warning (7a) Provides warning information by LHTS integratingvehicle speed with knowledge of road geometry. (7b) Provides warninginformation by LHTS integrating environmental conditions with roadsurface conditions. (7c) Provides warning information on road LHTSgeometry by integrating vehicle speed, road conditions, and roadgeometry. (7d) Provides warning information on LHTS upcoming trafficsigns and signalized intersections. (7e) Provides warnings thatreplicate one or LHTS more types of road signs in complex or hazardoushighway locations. (8) Automatic Collision Notification (8a)Automatically transmits position/loca- LHTS tion of vehicle, wheninvolved in a collision, using PSAP. (8b) Automatically provides crashseverity LHTS information from vehicle to PSAP. (8c) Integrates withmanually activated LHTS systems for requesting roadside assistance.

This service is already implemented on GM's OnStar system.

(9) Smart Restraints and Occupant Protection Systems Gen. 0 Gen. I Gen.II (9a) Provides advance warning of an im- LHTS pending frontalcollision to the vehicle protection system (9b) Provides advance warningof an im- LHTS pending side collision to the vehicle protection system.(9c) Pre-deploys appropriate occupant pro- LHTS tection systems invehicle prior to impact.

The scanning laser radar will identify both large and small objects.

(10) Navigation/Routing Gen. 0 Gen. I Gen. II (10a) Provides locationinformation to the LHTS driver. (10b) Provides route guidanceinformation to LHTS the driver. (10c) Provides road geometry data toCAS. LHTS (10d) Provides location data to CAS. LHTS (10e) Displays onlythe traffic information LHTS that is applicable to vehicle location androute. (10f) Provides optimal routing based on LHTS driver preferences.(10g) Uses real-time traffic information in LHTS calculations of optimalroutes.

The information for this service will be in the map database.

(11) Real-Time Traffic and Traveler Information Gen. 0 Gen. I Gen. II(11a) Accesses in-vehicle databases to LHTS determine vehicle locationand route guid- ance instructions. (11b) Receives travel-relatedinformation from the infrastructure (roadside or wide- areatransmissions) to include: (11b-i) Motorist and traveler services LHTSinformation. (11b-ii) Safety and advisory information. LHTS (11b-iii)Real-time updates on congestion; LHTS work zones; environmental and roadsurface conditions. (11c) Provides an integrated approach to the LHTSpresentation of information to the driver for safety warnings and othertask-related advisories. (11d) Provides the capability of reacting toLHTS information on environmental and road conditions (augments staticdatabase). (12) Driver Comfort and Convenience NA

This is also already being done by various automobile manufacturersindependently.

(13) Vehicle Stability Warning and Assistance Gen. 0 Gen I Gen. II (13a)Measures rollover stability properties HTS of a typical heavy vehicle.(13b) Provides the driver with a graphical NA depiction of the vehicle'sloading condition relative to its rollover propensity. (13c) Provides anactive brake control HTS system to selectively apply brakes to stabi-lize the vehicle. (13d) Integrates the active brake control with HTSelectronic braking system technology and infrastructure-providedinformation.

The vehicle and road properties must be known prior to the danger orelse it is too late. In Phase One the vehicle inertial properties willbe determined by monitoring its response to known road inputs.

(14) Driver Condition Warning Gen. 0 Gen. I Gen. II (14a) Provides adriver monitoring and warn- LHTS ing capability to alert the driver ofdrowsi- ness or other types of impairments (CVO or Transit first).

The system senses when driver goes off the road or commits otherinfractions and then tests driver response by turning on the hazardlights which the driver must turn off, for example.

(15) Vehicle Diagnostics Gen. 0 Gen. I Gen. II (15a) Monitors anddisplays vehicle safety- LHTS related functions (i.e., braking systeminte- grity, tire pressure, sensor and actuator per- formance, andcommunications system).

Cars do not now have a general diagnostic system. One is disclosed inU.S. Pat. No. 5,809,437.

(16) Cargo Identification Gen. 0 Gen. I Gen. II NA

Cargo information can be part of the vehicle ID message.

(17) Automated Transactions Gen. 0 Gen. I Gen. II (17a) Provides thedriver with the capability LHTS of ETC and the payment of parking feesand transit fares. (17b) Provides heavy-vehicle drivers with LHTS thecapability of electronically filing cre- or NA dentials and permitverifications.

Automated transactions can be automatic with RtZF based on vehicle ID.

(18) Safety Event Recorder Gen. 0 Gen. I Gen. II (18a) Records selecteddriver and vehicle LHTS parameters to support the reconstruction of anaccident. (18b) Provides a notification system for LHTS transmission ofcollision data to the emergency service provider.

The Phase Zero recorder in the 1000 vehicles will record the following;(1) Time, place and velocity when infractions are sensed. (2) Weather,temperature, illumination etc. (3) Brake pressure, throttle, steeringangle etc. (4) Occupant position. (5) In vehicle still pictures. (6)Number of satellites observed. (7) State of DGPS signals. (8) State ofthe system.

(19) Obstacle/Pedestrian Detection Gen. 0 Gen. I Gen. II (19a) Warns thedriver when pedestrians, LHTS vehicles, or obstacles are in closeproximity to the driver's intended path using onboard sensors. (19b)Warns the driver when pedestrians, NA vehicles, or obstacles are inclose proximity to the driver's intended path using infra-structure-based sensors.

In Phase One scanning laser radar, lenses & range gating will be used tocover all vehicle sides.

(20) Tight Maneuver/Precision Docking Gen. 0 Gen. I Gen. II (20a)Provides sensors to continuously calcu- HT late the lateral distance tothe curb, front and rear, in order to park the vehicle in a preciselocation. (20b) Provides sensors to continuously calcu- HT late thelongitudinal distance to the end of the vehicle loading area in order topark the vehicle in the precise location (20c) Provides the driver withthe ability to HT override automated system by pressing brakes orsteering in emergency situations.

This service can be provided in Phase Zero. This will probably requireMIR triads or equivalent.

Gen. 0 Gen. I Gen. II (21) Transit Passenger Monitoring NA (22) TransitPassenger Information NA

RtZF can provide location information.

(23) Fully Automated Control at Certain Facilities Gen. 0 Gen. I Gen. IINA

RtZF could provide,accurate position information to support thisservice.

(24) Low-Friction Warning and Control Assist Gen. 0 Gen. I Gen. II (24a)Provides drivers with a warning to in- LHTS dicate reduced traction,detected by onboard sensors. (24b) Provides drivers with control assistLHTS capabilities to help the driver regain control of the vehicle.

Historical road data and weather prediction plus roadway sensors andprobes will provide this service in Phase One.

(25) Longitudinal Control Gen. 0 Gen. I Gen. II (25a) Provides normalcruise control. LHTS (25b) Provides a cooperative intelligent LHTScruise control. (25c) Monitors location and relative speed of LHTSnear-by vehicles. (25d) Provides automatic speed adjustment LHTS bycoasting or downshifting to maintain a safe operating envelope. (25e)Provides a system capable of detecting LHTS a vehicle located ahead inthe same lane of traffic that is either traveling at any speed or fullystopped. (25f) Provides a full-range of braking capa- LHTS bilities andoperating speeds to be used for all driving situations, includingstop-and-go traffic.

Automatic Cruise Control (ACC) is provided in Phase Zero. The rest arebasic services to be provided in Phase One.

(26) Lateral Control Gen. 0 Gen. I Gen. II (26a) Provides a sensorcapable of detecting LHTS the center of the lane using infrastructuresupport such as accurately painted lane marker stripes, embeddedmagnetic nails, or radar-reflective stripes. (26b) Provides automaticsteering control LHTS that will maintain vehicle position in the centerof the lane.

These are the main services to be provided in Phase Zero.

This paper further goes into considerable discussion on various means ofcommunication between a vehicle and other vehicles as well as theinfrastructure. However, no recommendations are made forvehicle-to-vehicle communication technologies.

The above references, among other things, demonstrate that there arenumerous methods and future enhancements planned that will providecentimeter level accuracy to an RtZF equipped vehicle. There are manyalternative paths that can be taken but which ever one is chosen theresult is clear that such accuracies are within the start of the arttoday.

Limitations of the Prior Art

Previous inventions have attempted to solve the collision avoidanceproblem for each vehicle independently of the other vehicles on theroadway. Systems that predict vehicle trajectories generally failbecause two vehicles can be on a collision course and within the last0.1. second a slight change of direction avoids the collision. This is acommon occurrence that depends on the actions of the individual driversand no collision avoidance system now in existence is believed to beable to differentiate this case from an actual collision. In the presentinvention, every equipped vehicle will be confined to a corridor and toa position within that corridor where the corridor depends on sub-meteraccurate digital maps. Only if that vehicle deviates from the corridorwill an alarm sound or the vehicle control system take over control ofthe vehicle sufficiently to prevent the vehicle from leaving itscorridor if an accident would result from the departure from thatcorridor.

Additionally, no prior art system has successfully used the GPSnavigational system, or an augmented DGPS to locate a vehicle on aroadway with sufficient accuracy that that information can be used toprevent the equipped vehicle from leaving the roadway or strikinganother similarly equipped vehicle.

Prior art systems in addition to being poor at locating potentialhazards on the roadway, have not been able to ascertain whether they arein fact on the roadway of off on the side, whether they are threateningvehicles, static signs over overpasses etc. In fact no credible attemptto date has been made to identify or categorize objects which may impactthe subject vehicle.

The RtZF™ system of this invention also contemplates a different kind ofinterrogating system. It is based on scanning infrared laser radar withrange gating. This system, when used in conjunction with accurate maps,will permit a precise imaging of an object on the road in front of thevehicle, for example, permitting it to be identified (using neuralnetworks) and its location, velocity and the probability of a collisionto be determined.

In particular, the system of this invention is particularly effective ineliminating accidents at intersections caused by drivers running stopsigns, red stoplights and turning into oncoming traffic. There areapproximately one million such accidents and they are the largest killerin older drivers who frequently get confused at intersections.

SUMMARY AND OBJECTS OF THE INVENTION

The above and other objects and advantages of the present invention areachieved by the preferred embodiments that are summarized and describedin detail below.

It is an object of the present invention to provide a new and improvedmethod and arrangement for mapping a road.

It is another object of the present invention to provide a new andimproved method and arrangement for mapping a road quickly and moreprecisely than possible using prior art systems.

In order to achieve these objects, an arrangement for attaching to avehicle to enable mapping of a road during travel of the vehiclecomprises a first data acquisition module adapted to be arranged on afirst side of the vehicle and a second data acquisition module adaptedto be arranged on a second side of the vehicle. Each module comprises aGPS receiver and an antenna for enabling a determination of the positionof the vehicle to be obtained and a linear camera adapted to provideone-dimensional images of an area on a respective one of the first andsecond sides of the vehicle. The linear cameras provide images of avertical plane perpendicular to the road such that a view of the road ina direction perpendicular to the road is obtained and information aboutthe road is obtainable from that view. A processor unit is coupled tothe modules and forms a map database of the road by correlating theposition of the vehicle on the road and the information about the road.The processor unit can be resident in the vehicle or data can beobtained and stored in a memory unit in the vehicle and the map databaseformed later from the stored data.

The linear cameras may be linear CCD, CMOS and other light sensitivearrays. The light cameras may comprise a lens for providing a field ofview from an approximate center of the vehicle to the horizon wherebythe linear cameras are thus adapted to record one-dimensional picturescovering the entire road starting with approximately the center of alane in which the vehicle travels and extending out to the horizon.

Each module can also include a scanning laser radar adapted to transmitwaves downward in a plane perpendicular to the road and receivereflected radar waves to thereby provide information about distancebetween the laser radar and the ground which constitutes informationabout the road. The laser radar may be coordinated or synchronized withthe linear camera of its module to cover a common field of view. Thelaser radars may be pulse-modulated or tone-modulated. In oneimplementation, laser radars are used with the linear cameras being anoptional enhancement.

Each module can also comprise a video camera adapted to provide imagesof an area in front of the vehicle whereby images of an environment ofthe road including traffic signs and other informational displays areobtained and provide information about the road. Such information isused to form the map database. The video cameras may be color videocameras, high-speed video cameras, wide angle cameras, telescopiccameras, black and white video cameras and infrared cameras. Artificialillumination devices can be incorporated into or with the modules toprovide artificial illumination at least when an absence of sufficientnatural illumination for obtaining images from the video cameras isdetected. In this regard, a laser scanner may be adapted to illuminate aparticular part of the area in front of the vehicle with a bright spot.A scanning laser rangefinder can be arranged in connection with at leastone of the video cameras for determining the distance to particularobjects in the images obtained by that video camera whereby the distanceconstitutes information about the road which is used to form the mapdatabase.

A method for mapping a road entails arranging a first data acquisitionmodule on a first side of the vehicle, arranging a second dataacquisition module on a second side of the vehicle, each modulecomprising a GPS receiver and an antenna and a linear camera oriented toprovide one dimensional images in a vertical plane of an area on arespective one of the first and second sides of the vehicle, operatingthe vehicle on the road while continually obtaining the position of thevehicle using the GPS receiver and antenna and obtaining images from thelinear cameras of vertical planes perpendicular to the road and forminga map database of the road by correlating the position of the vehicle onthe road and information about the road obtained from the images fromthe linear cameras. The aspects of the arrangements described above canbe incorporated into the mapping method.

Another method for mapping a road comprises (he steps of arranging afirst data acquisition module on a first side of the vehicle, arranginga second data acquisition module on a second side of the vehicle, eachmodule comprising a GPS receiver and an antenna and a scanning laserradar oriented to transmit waves downward in a plane perpendicular tothe road and receive reflected radar waves, operating the vehicle on theroad while continually obtaining the position of the vehicle using theGPS receiver and antenna and obtaining information about the distancebetween the laser radars and the ground by transmitting and receivingradar waves and forming a map database of the road by correlating theposition of the vehicle on the road and the information about distancebetween the laser radars and the ground. The aspects of the arrangementsdescribed above can be incorporated into this mapping method.

Another aspect of the invention is a computer controlled vehicle andobstacle location system and method which includes the steps ofreceiving continuously from a network of satellites on a firstcommunication link at one of a plurality of vehicles, GPS rangingsignals for initially accurately determining, in conjunction withcentimeter accurate maps, the host vehicle's position on a roadway on asurface of the earth; receiving continuously at the host vehicle on asecond communication link from a station or satellite, DGPS auxiliaryrange correction signals for correcting propagation delay errors in theGPS ranging signals; determining continuously at the host vehicle fromthe GPS, DGPS, and accurate map database signals host vehicle's positionon the surface of the earth with centimeter accuracy; communicating thehost vehicle's position to another one of the plurality of vehicles, andreceiving at the host vehicle, location information from at least one ofa plurality of other vehicles; determining whether the other vehiclerepresents a collision threat to the host vehicle based on its positionrelative to the roadway and the host vehicle and generating a warning orvehicle control signal response to control the vehicles motion laterallyor longitudinally to prevent a collision with the other vehicle.

In some implementations of the invention, the detecting step includesdetecting objects by scanning with one or more cameras, radars or laserradars located on the host vehicle. The analyzing step includesprocessing and analyzing digital signals indicative of video imagesdetected by the one or more cameras, radars or laser radars, andprocessing and analyzing the digital signals using pattern recognitionand range determination algorithms. The objects detected may includefixed or moving, or known or unknown obstacles, people, bicycles,animals, or the like.

A still further feature of this aspect of the invention is to operateone or more of the following systems depending on the kind of responsedetermined by the neural fuzzy logic control system: a brake pedal,accelerator pedal, steering system (e.g., steering wheel), horn, light,mirror, defogger and communication systems.

The first phase of implementation of this invention can be practicedwith only minor retrofit additions to the vehicle. These include theaddition of a differential GPS system and an accurate map database. Inthis first phase, the driver will only be warned when he or she is aboutto depart from the road surface. During the second phase of practicingthis invention, the system will be augmented with a system that willprevent the operator from leaving the assigned corridor and inparticular leaving the road at high speed. In further phases of theimplementation of this invention, additional systems will be integratedwhich will scan the roadway and act to prevent accidents with vehiclesthat do not have the system installed. Also communication systems willbe added to permit the subject vehicle to communicate its position,velocity, etc., to other nearby vehicles which are also equipped with asystem.

A primary preferred embodiment of the system, therefore, is to equip avehicle with a DGPS system, a laser gyro or other inertial guidancesystem, vehicle steering, throttle and brake control apparatus, asub-meter accurate digital map system with the relevant maps (or abilityto access the relevant maps), a scanning pulsed infrared laser radar, asystem for sensing or receiving signals from a highway-based preciseposition determination system, and communications systems for (1)sending and receiving data from similarly equipped vehicles, (2)receiving updated maps and map status information, and (3) receivingweather and road condition information. A preferred embodiment for theinfrastructure enhancements includes a DGPS system, a micropower impulseradar (MIR), Radio Frequency Identification (RFID) based or equivalentprecise position determining system and local weather and road conditiondetermination and transmission system.

This invention is thus a method and apparatus for preventing vehicleaccidents. A vehicle is equipped with a differential GPS (DGPS)navigational system as well as an inertial navigation subsystem. Part ofthe system can be an array of infrastructure stations that permit thevehicle to exactly determine its position at various points along itspath. Such stations would typically be located at interals such as every50 miles along the roadway, or more or less frequently depending onrequirements as described below. These stations permit the vehicle tobecome its own DGPS station and thus to correct for the GPS errors andto set the position of the vehicle based initial guidance system. Italso provides sufficient information for the vehicle to use the carrierfrequency to determine its absolute position to within a few centimetersor better for as long as satellite locks are maintained. Data is alsoavailable to the vehicle that provides information as to the edges ofthe roadway, and edges of the lanes of the roadway, at the location ofthe vehicle so that the vehicle control system can continuouslydetermine its location relative to the roadway edges and/or lane edges.In the initial implementation, the operator operates his or her vehicleand is unaware of the presence of the accident avoidance system. If,however, the operator falls asleep go or for some other reason attemptsto drive off the roadway at high speed, the system will detect that thevehicle is approaching an edge of the roadway and will either sound analarm or prevent the vehicle from leaving the roadway when doing sowould lead to an accident. In some cases, the system will automaticallyreduce the speed of the vehicle and stop it on the shoulder of theroadway.

It is important to note that the invention as described in the aboveparagraph is in itself a significant improvement to automotive safety.Approximately half of all fatal accidents involve only a single vehiclethat typically leaves the roadway and impacts with a roadside obstacle,cross an yellow line or run a red light or stop sign. This typicallyhappens when the driver in under the influence of alcohol or drugs, hasa medical emergency or simply falls asleep. If this cause of accidentscould be eliminated, the potential exists for saving many thousands ofdeaths per year when all vehicles are equipped with the system of thisinvention. This would make this the single greatest advance inautomotive safety surpassing both seatbelts and airbags in lifesavingpotential.

A first improvement to the basic invention is to provide the vehiclewith a means using radar, laser radar, optical or infrared imaging, or asimilar technology, to determine the presence, location and velocity ofother vehicles on the roadway that are not equipped with the accidentavoidance system. The accident avoidance system (RtZF™) of thisinvention will not be able to avoid all accidents with such vehicles forthe reasons discussed above, but will be able to provide a level ofprotection which is believed to surpass all known prior art systems.Some improvement over prior art systems will result from the fact thatthe equipped vehicle knows the location of the roadway edges, as well asthe lane boundaries, not only at the location of the equipped vehiclebut also at the location of the other nearby vehicles. Thus, theequipped vehicle will be able to determine that an adjacent vehicle hasalready left its corridor and warn the driver or initiate evasiveaction. In prior art systems, the location of the roadway is not knownleading to significantly less discrimination ability.

A second improvement to the RtZF of this invention is to providecommunication ability to other nearby similarly equipped vehiclespermitting the continuous transmission and reception of the locations ofall equipped vehicles in the vicinity. With each vehicle knowing thelocation, and thus the velocity, of all potential impacting vehicleswhich are equipped with the RtZF, collisions between vehicles can bereduced and eventually nearly eliminated when all vehicles are equippedwith the RtZF.

A third improvement comprises the addition of software to the systemthat permits vehicles on specially designated vehicle corridors for theoperator to relinquish control of the vehicle to the vehicle-basedsystem, and perhaps to a roadway computer system. This then permitsvehicles to travel at high speeds in a close packed formation therebysubstantially increasing the flow rate of vehicles on a given roadway.Naturally, in order to enter the designated corridors, a vehicle wouldbe required to be equipped with the RtZF. Similarly, this then providesan incentive to vehicle owners to have their vehicles so equipped sothat they can enter the controlled corridors and thereby shorten theirtravel time.

Prior art systems require expensive modifications to highways to permitsuch controlled high speed close packed travel. Such modifications alsorequire a substantial infrastructure to support the system. The RtZF ofthe present invention, in its simplest form, does not require anymodification to the roadway but rather relies primarily on the GPS orsimilar satellite system. The edge and lane boundary information iseither present within the vehicle RtZF memory or transmitted to thevehicle as it travels along the road. The permitted speed of travel isalso communicated to the vehicles on the restricted corridor and thuseach vehicle travels at the appointed speed. Since each vehicle knowsthe location of all other vehicles in the vicinity, should one vehicleslow down, due to an engine malfunction, for example, appropriate actioncan be taken to avoid an accident. Vehicles do not need to travel ingroups as suggested and required by some prior art systems. Rather, eachvehicle may independently enter the corridor and travel at the systemdefined speed until it leaves, which may entail notifying the system ofa destination.

Another improvement involves the transmission of additional dataconcerning weather conditions, traffic accidents etc. to the equippedvehicle so that the speed of that vehicle can be limited to a safe speeddepending on road conditions, for example. If moisture is present on theroadway and the temperature is dropping to the point that ice might bebuilding up on the road surface, the vehicle can be notified by theroadway information system and prevented from traveling at an unsafespeed.

Other objectives and advantages of the RtZF system of this inventiondisclosed herein include:

1. To provide a system based partially on the global positioning system(GPS) or equivalent that permits an onboard electronic system todetermine the position of a vehicle with an accuracy of 1 meter orbetter.

2. To provide a system which permits an onboard electronic system todetermine the position of the edges and/or lane boundaries of a roadwaywith an accuracy of 1 meter or less in the vicinity of the vehicle.

3. To provide a system which permits an onboard vehicle electronicsystem to determine the position of the edges and/or lane boundaries ofa roadway relative to the vehicle with an accuracy of less than about 10centimeters.

4. To provide a stem that substantially reduces the incidence of singlevehicle accidents caused by the vehicle inappropriately leaving theroadway at high speed.

5. To provide a system which does not require modification to a roadwaywhich permits high speed controlled travel of vehicles on the roadwaythereby increasing the vehicle flow rate on congested roads.

6. To provide a collision avoidance system comprising a sensing systemresponsive to the presence of at least one other vehicle in the vicinityof the equipped vehicle and means to determine the location of the othervehicle relative to the lane boundaries of the roadway and therebydetermine if the other vehicle has strayed from its proper position onthe highway thereby increasing the risk of a collision, and takingappropriate action to reduce that risk.

7. To provide a means whereby vehicles near each other can communicatetheir position and/or their velocity to each other and thereby reducethe risk of a collision.

8. To provide a means for accurate maps of a roadway to be transmittedto a vehicle on the roadway.

9. To provide a means for weather, road condition and/or similarinformation can be communicated to a vehicle traveling on a roadway plusmeans within the vehicle for using that information to reduce the riskof an accident.

10. To provide a means and apparatus for a vehicle to precisely know itslocation at certain positions on a road by passing through or over aninfrastructure based local subsystem thereby permitting the vehicleelectronic systems to self correct for the satellite errors making thevehicle for a brief time a DGPS station.

11. To utilize government operated navigation aid systems such as theWAAS and LARS as well as other available or to become available systemsto achieve sub-meter vehicle location accuracies.

12. To utilize the OpenGIS™ map database structure so as to promote opensystems for accurate maps for the RtZF™ system.

13. To eliminate intersection collisions caused by a driver running ared light or stop sign.

14. To eliminate intersection collisions caused by a driver executing aturn into oncoming traffic.

In contrast to some prior art systems, with the RtZF™ system inaccordance with the invention, especially when all vehicles areappropriately equipped, automatic braking of the vehicle should rarelybe necessary and steering and throttle control should in most cases besufficient to prevent accidents. In most cases, braking means theaccident wasn't anticipated.

It is important to understand that this is a process control problem.The process is designed so that it should not fail and thus allaccidents should be eliminated. Events that are troublesome to thesystem include a deer running in front of the vehicle, a box falling offof a truck, a rock rolling onto the roadway and a catastrophic failureof a vehicle. Continuous improvement to the process is thus requiredbefore these events are substantially eliminated. Each individual driverand vehicle control system is part of the system and upon observing thatsuch an event has occurred he or she should have the option of stoppingthe process to prevent or mitigate an emergency. All equipped vehiclestherefore have the capability of communicating that the process isstopped and therefore that the vehicle speed, for example, should besubstantially reduced until the vehicle has passed the troubled spot oruntil the problem ceases to exist. In other words, each driver is partof the process.

The RtZF™ system in accordance with the invention will thus start simpleby reducing single vehicle accidents and evolve. The system has thecapability to solve the entire problem by eliminating automobileaccidents.

This invention is a method and apparatus for eliminating accidents byaccurately determining the position of a vehicle, accurately knowing theposition of the road and communicating between vehicles and between thevehicle and the infrastructure supporting travel. People get intoaccidents when they go too fast for the conditions and when they get outof their corridor. This invention eliminates these and other causes ofaccidents. In multilane highways, this system prevents people fromshifting lanes if there are other vehicles in the blind spot, thus,solving the blind spot problem. The vehicle would always be travelingdown a corridor where the width of the corridor may be a lane or theentire road width or something in between depending on road conditionsand the presence of other vehicles.

The invention is implemented through the use of both an inertialnavigation system (INS) and a DGPS, in some cases with carrier frequencyenhancement. Due to the fact that the signals from at least four GPS orGLONASS satellites are not always available and to errors caused bymultiple path reception from a given satellite, the DGPS systems cannotbe totally relied upon. Therefore the INS is a critical part of thesystem. This will improve as more satellites are launched and additionalground stations are added. It will also significantly improve when theWAAS and LAAS systems are implemented and refined to work with landvehicles as well as airplanes.

Other improvements will now be obvious to those skilled in the art. Theabove features are meant to be illustrative and not definitive.

BRIEF DESCRIPTION OF THE DRAWINGS

The various hardware and software elements used to cam, out theinvention described herein are illustrated in the form of systemdiagrams, block diagrams, flow charts, and depictions of neural networkalgorithms and structures. The preferred embodiment is illustrated inthe following figures:

FIG. 1 illustrates the GPS satellite system with the 24 satellitesrevolving around the earth.

FIG. 2 illustrates four GPS satellites transmitting position informationto a vehicle and to a base station which in turn transmits thedifferential correction signal to the vehicle.

FIG. 3 illustrates a WADGPS system with four GPS satellites transmittingposition information to a vehicle and to a base station which in turntransmits the differential correction signal to the vehicle.

FIG. 4 is a logic diagram showing the combination of the GPS system andan inertial navigation system.

FIG. 5 is a block diagram of the overall vehicle accident avoidance,warning, and control system and method of the present inventionillustrating system sensors, radio transceivers, computers, displays,input/output devices and other key elements.

FIG. 6 is a block diagram of an image analysis computer of the type thatcan be used in the accident avoidance system and method of thisinvention.

FIG. 7 illustrates a vehicle traveling on a roadway in a definedcorridor.

FIG. 8 illustrated two adjacent vehicles traveling on a roadway andcommunicating with each other.

FIG. 9 is a schematic diagram illustrating a neural network of the typeuseful in the image analysis computer of FIG. 5.

FIG. 10 is a schematic diagram illustrating the structure of a nodeprocessing element in the neural network of FIG. 9.

FIG. 11 illustrates the use of a precise positioning system employingthree micropower impulse radar transmitters or three RFID tags in aconfiguration to allow a vehicle to accurately determine its position.

FIG. 12a is a flow chart of the method in accordance with the inventionfor preventing run off the road accidents.

FIG. 12b is a flow chart of the method in accordance with the inventionfor preventing yellow line crossing accidents.

FIG. 12c is a flow chart of the method in accordance with the inventionfor preventing stoplight running accidents.

FIG. 13 illustrates an intersection with stop signs on the lesser roadwhere there is a potential for a front to side impact and a rear endimpact.

FIG. 14 illustrates a blind intersection with stoplights where there isa potential for a front side to front side impact.

FIG. 15 illustrates an intersection where there is a potential for afront-to-front impact as a vehicle turns into oncoming traffic.

FIG. 16A is a side view of a vehicle equipped with a road-mappingarrangement in accordance with the invention.

FIG. 16B is a front perspective view of a vehicle equipped with theroad-mapping arrangement in accordance with the invention.

FIG. 17. is a schematic perspective view of a data acquisition module inaccordance with the invention.

FIG. 17A is a schematic view of the data acquisition module inaccordance with the invention.

FIG. 18 shows the view of a road from the video cameras in both of thedata acquisition modules.

DETAILED DISCUSSION OF THE INVENTION

a. Scope of the Disclosure

The preferred embodiments of the inventions are described in the Figuresand Detailed Description below. Unless specifically noted, it isapplicants intention that the words and phrases in the specification andclaims be given the ordinary and accustomed meaning to those of ordinaryskill in the applicable art(s). If applicants intend any other meaning,they will specifically state they are applying a special meaning to aword or phrase.

Likewise, applicants' use of the word “function” in the DetailedDescription is not intended to indicate that the seeks to invoke thespecial provisions of 35 U.S.C. Section 112, paragraph 6 to define hisinvention. To the contrary, if applicants wish to invoke the provisionof 35 U.S.C. Section 112, paragraph 6, to define their invention, theywill specifically set forth in the claims the phrases “means for” or“step for” and a function, without also reciting in that phrase anystructure, material or act in support of the function. Moreover, even ifapplicants invoke the provisions of 35 U.S.C. Section 112, paragraph 6,to define their invention, it is applicants intention that theirinventions not be limited to the specific structure, material or actsthat are described in their preferred embodiments. Rather, if applicantsclaim their invention by specifically invoking the provisions of 35U.S.C. Section 112, paragraph 6. it is nonetheless their intention tocover and include any and all structures, materials or acts that performthe claimed function, along with any and all known or later developedequivalent structures, materials or acts for performing the claimedfunction.

For example, the present inventions make use of GPS satellite locationtechnology, including the use of MIR or RFID triads, to derive kinematicvehicle location and motion trajectory parameters for use in a vehiclecollision avoidance system and method. The inventions described hereinare not to be limited to the specific GPS devices or PPS devicesdisclosed in the preferred embodiments, but rather, are intended to beused with any and all such applicable satellite location devices,systems and methods, as long as such devices, systems and methodsgenerate input signals that can be analyzed by a computer to accuratelyquantify vehicle location and kinematic motion parameters in real time.Thus, the GPS devices and methods shown and referenced generallythroughout this disclosure, unless specifically noted, are intended torepresent any and all devices appropriate to determine such location andkinematic motion parameters.

Likewise, for example, the present inventions generate surveillanceimage information for analysis by scanning using any applicable image orvideo scanning system or method. The inventions described herein are notto be limited to the specific scanning or imaging devices disclosed inthe preferred embodiments, but rather, are intended to be used with anyand all applicable electronic scanning devices, as long as the devicecan generate an output signal that can be analyzed by a computer todetect and categorize objects. Thus, the scanners or image acquisitiondevices are shown and referenced generally throughout this disclosure,and unless specifically noted, are intended to represent any and alldevices appropriate to scan or image a given area. Accordingly, thewords “scan” or “image” as used in this specification should beinterpreted broadly and generically.

Further, there are disclosed several computers or controllers, thatperform various control operations. The specific form of computer is notimportant to the invention. In its preferred form, applicants divide thecomputing and analysis operations into several cooperating computers ormicroprocessors. However, with appropriate programming well known tothose of ordinary skill in the art, the inventions can be implementedusing a single, high power computer. Thus, it is not applicantsintention to limit their invention to any particular form of computer.

Further examples exist throughout the disclosure, and it is notapplicants intention to exclude from the scope of his invention the useof structures, materials, or acts that are not expressly identified inthe specification, but nonetheless are capable of performing a claimedfunction.

b. Overview of the Invention

The above and other objects are achieved in the present invention whichprovides motor vehicle collision avoidance, warning and control systemsand methods using GPS satellite location systems augmented with precisepositioning systems to provide centimeter location accuracy, and toderive vehicle attitude and position coordinates and vehicle kinematictracking information. GPS location and computing systems beingintegrated with vehicle video scanning, radar, laser radar, and on boardspeedometer and/or accelerometers and gyroscopes to provide accuratevehicle location information together with information concerninghazards and/or objects that represent impending collision situations foreach vehicle. Advanced image processing techniques are used to quantifyvideo information signals and to derive vehicle warning and controlsignals based upon detected hazards.

Outputs from multiple sensors as described above are used in onboardvehicle neural network and neural-fuzzy system computing algorithms toderive optimum vehicle warning and control signals designed to avoidvehicle collisions with other vehicles or with other objects or hazardsthat may be present on given roadways. In a preferred embodiment, neuralfuzzy control algorithms are used to develop coordinated braking,acceleration and steering control signals to control individual vehiclesin an optimal manner to avoid or minimize the effects of potentialcollisions. Video, radar, laser radar and GPS position and trajectoryinformation are made available to each individual vehicle describing themovement of that vehicle and other vehicles in the immediate vicinity ofthat vehicle.

In addition, hazards or other obstacles that may represent a potentialdanger to a given vehicle are also included in the neural fuzzycalculations. Object, obstacles and/or other vehicles located anywhereto the front, rear or sides of a given vehicle are considered in thefuzzy logic control algorithms in the derivation of optimal control andwarning signals.

Description of GPS System

Background of GPS

Referring to FIG. 1, the presently implemented Global Positioning Systemwith its constellation of 24 satellites 2 is truly revolutionizingnavigation throughout the world. The satellites orbit the Earth in sixorbits 4. However, in order: to reach its full potential for navigation,GPS needs to be augmented both to improve accuracy and to reduce thetime needed to inform a vehicle driver of a malfunction of a GPSsatellite, the so-called integrity problem.

The Global Positioning System (GPS) is a satellite-based navigation andtime transfer system developed by the U.S. Department of Defense. GPSserves marine airborne and terrestrial users, both military andcivilian. Specifically, GPS includes the Standard Positioning Service(SPS) that provides civilian users with 100 meter accuracy as to thelocation or position of the user. It also serves military users with thePrecise Positioning Service that provides 20-meter accuracy for theuser. Both of these services are available worldwide with no requirementfor any local equipment.

Differential operation of GPS is used to improve the accuracy andintegrity of GPS. Differential GPS places one or more high quality GPSreceivers at known surveyed locations to monitor the received GPSsignals. This reference station(s) estimates the slowly varyingcomponents of the satellite range measurements, and forms a correctionfor each GPS satellite in view. The correction is broadcast to all DGPSusers within the coverage area of the broadcast facilities.

DGPS

For a good discussion of DGPS, for following paragraphs are reproducedfrom OMNISTAR:

“The new OMNISTAR Model 6300A offers unprecedented versatility forportable, real-time, DGPS positioning. It can improve the accuracy of aGPS receiver by as much as 100 times. If your product or service needsprecise positioning information. then chances are good that OMNISTAR cansupply that need; and at a reasonable cost.

“What is a “DGPS” System?

“OMNISTAR is a Differential GPS (DGPS) System. It is capable ofimproving regular GPS to sub-meter accuracy. GPS computes a user'sposition by measuring ranges (actually, pseudoranges; which are rangesthat are calculated by an iterative process) to three or more GPSsatellites simultaneously. The Department of Defense (DOD) isintentionally limiting the accuracy of the calculation by continuouslychanging the onboard clock on the satellites. This process is calledSelective Availability, or “SA”. This appears as a continuous variationin the user's position. Using GPS in an uncorrected (stand-alone) mode,a user's calculated position mill continuously move around the trueposition in a near-random pattern. The indicated position may move outas far as 100 meters from the true position. The randomness makes itimpossible to predict. If a user samples the position data over a longperiod of time, such as 24 hours, the average or mean will likely bewithin a meter of the true position. In statistical terms, the standarddeviation will be approximately 15 to 20 meters in each horizontalcoordinate.

“A DGPS System generates corrections for SA and other errors. This isaccomplished by the use of one or more GPS “Base Stations” that measurethe errors in the GPS system and generates corrections. A “real-time”DGPS System not only generates the corrections, but provides somemethodology for getting those corrections to users as quickly aspossible. This always involves some type of radio transmission system.They may use microwave systems for short ranges, low frequencies formedium ranges and geostationary satellites for coverage of entirecontinents.

“The method of generating corrections is similar in most DGPS systems. AGPS base station tracks all GPS Satellites that are in view at itslocation. The internal processor knows the precise surveyed location ofthe base station antenna, and it can calculate the location in space ofall GPS satellites at any time by using the epheremis that is a part ofthe normal broadcast message from all GPS satellites. From these twopieces of information, an expected range to each satellite can becomputed at any time. The difference between that computed range and themeasured range is the range error. If that information can quickly betransmitted to other nearby users, they can use those values ascorrections to their own measured GPS ranges to the same satellites. Thekey word is “quickly”, because of the rapid change in the SA errors. Inmost radio systems, bandwidth is a finite limitation which dictates howmuch data can be sent in a given time period. That limitation can beeased somewhat by having the GPS base station software calculate therate of change of the errors and add that information as part of thecorrection message. That term is called the range rate value and it iscalculated and sent along with the range correction term. The rangecorrection is an absolute value, in meters, for a given satellite at agiven time of day. The range rate term is the rate that correction ischanging, in meters per second. That allows GPS user sets to continue touse the “correction, plus the rate-of-change” for some period of timewhile it's waiting for a new message. The length of time you cancontinue to use that data without an update depends on how well therange rate was estimated. In practice, it appears that OMNISTAR wouldallow about 12 seconds before the DGPS error would cause a one meterposition error. In other words, the “age of data” can be up to 12seconds before the error from that term would cause a one meter positionerror. OMNISTAR transmits a new correction message every two andone/half seconds, so even if an occasional message is missed, the user's“age of data” is still well below 12 seconds.

“What is unique about the OMNISTAR DGPS system?

“The OMNISTAR DGPS System was designed with the following objectives:(1) continental coverage; (2) sub-meter accuracy over the entirecoverage area; and (3) a portable system (backpack). The first objectivedictated that the transmission system had to be from a geostationarysatellite. We purchased a transponder on satellite Spacenet 3, which islocated at 87 degrees West longitude. It has an antenna pattern thatcovers most of North America; specifically, all of the 48 states, thenorthern half of Mexico and the southern half of Canada. It also hassufficient power within that footprint that a tiny omnidirectionalantenna can be used at the user's receiver.

“The methodology developed by John E. Chance & Assoc. of using multipleGPS base stations in a user's solution and reducing errors due to theGPS signal traveling through the atmosphere, met the second objective.It was the first widespread use of a “Wide Area DGPS Solution”. It isable to use data from a relatively small number of base stations andprovide consistent accuracy over extreme distances. A unique method ofsolving for atmospheric delays and weighting of distant base stations,achieves sub-meter capability over the entire coverage area—regardlessof the user's proximity to any base station. This achieves a trulynationwide system with consistent characteristics. A user can take theequipment anywhere within the coverage area and get consistent results,without any intervention or intimate knowledge of GPS or DGPS.

“The units being sold today are sufficiently portable that they can usedin a backpack. They can include an internal GPS engine (optional) thatwill provide a complete solution in a single system package. All that isneeded is a data collector or notebook computer for display and storageof corrected GPS data.

“How does OMNI STAR work?

“The OMNISTAR Network consists of ten permanent base stations that arescattered throughout the Continental US, plus one in Mexico. Thesestations track all GPS Satellites above 5 degrees elevation and computecorrections every 600 milliseconds. The corrections are in the form ofan industry standard message format called RTCM-104, Version II. Thecorrections are sent to the OMMSTAR Network Control Center in Houstonvia lease lines, with a dial back-up. At the NCC these messages arechecked, compressed, and formed into a packet for transmission up to oursatellite transponder. This occurs approximately every 2 to 3 seconds. Apacket will contain the latest data from each of the 11 base stations.

“All OMNISTAR user sets receive these packets of data from the satellitetransponder. The messages are first decoded from the spread-spectrumtransmission format and then uncompressed. At that point, the message isan exact duplicate of the data as it was generated at each base station.Next, the atmospheric errors must be corrected. Every base stationautomatically corrects for atmospheric errors at it's location; but theuser is not at any of those locations, so the corrections are notoptimized for the user—and, OMNISTAR has no information as to eachindividual's location. If these errors are to be optimized for eachuser, then it must be done in each user's OMNISTAR. For this reason,each OMNISTAR user set must be given an approximation of its location.The approximation only needs to be within 50 to 100 miles of its trueposition. Given that information, the OMNISTAR user set can remove mostof the atmospheric correction from each Base Station message andsubstitute a correction for his own location. In spite of the looseapproximation of the user's location, this information is crucial to theOMNISTAR process. It makes the operation totally automatic and it isnecessary for sub-meter positioning. If it is totally ignored, errors ofup to ten meters can result.

“Fortunately, this requirement of giving the user's OMNISTAR anapproximate location is easily solved. If OMNISTAR is purchased with theoptional internal GPS receiver installed, the problem is taken care ofautomatically by using the position output of the GPS receiver as theapproximation. It is wired internally to do exactly that. An alternatemethod—when the internal GPS receiver is not present—is to use theuser's external GPS receiver for this function. In that case, the user'sreceiver must have an output message in one of the approved formats(NMEA) and protocols that OMNISTAR can recognize.

“That output can be connected back to the OMNISTAR set by using the samecable that normally supplies the RTCM-104 from OMNISTAR to the user'sGPS receiver. This method works perfectly well when all the requirementson format and protocol are met. There is a third method, where a useruses a notebook computer to type in an estimated location into the,OMNISTAR user set. Any location entered by this method is preserved—withan internal battery—until it is changed. This method works fine wherethe user does not intend to go more than 50-100 miles from some centrallocation.

“After the OMNISTAR processor has taken care of the atmosphericcorrections, it then uses it's location versus the eleven base stationlocations, in an inverse distance-weighted least-squares solution. Theoutput of that least-squares calculation is a synthesized RTCM-104Correction Message that is optimized for the user's location. It isalways optimized for the user's location that is input from the user'sGPS receiver or as an approximation that is typed in from a notebookcomputer. This technique is called the “Virtual Base Station Solution”.It is this technique that enables the OMNISTAR user to operateindependently and consistently over the entire coverage area withoutregard to where he is in relation to our base stations. As far as wehave determined, users are obtaining the predicted accuracy over theentire area.”

The above description is provided to illustrate the accuracy which canbe obtained from the DGPS system. It is expected that the WAAS systemwhen fully implemented sill provide the same benefits as provided by theOMNISTAR system. However, when the standard deviation of approximately0.5 meter is considered, it is evident that this WAAS system isinsufficient by itself and will have to be augmented by other systems toimprove the accuracy at least at this time.

GLONASS is a Russian system similar to GPS. This system providesaccuracy that is better than GPS with SA on and not as good as GPS withSA off. It is expected that SA will be removed before the systemdescribed herein is implemented.

The Projected Position Accuracy of GPS and GLONASS, Based on the CurrentPerformance is:

Horizontal Error (m) Vertical Error (m) (50%) (95%) (95%) GPS (SA off) 7 18 34 GPS (SA on) 27 72 135  GLONASS 10 26 45 GPS + GLONASS  9 20 38

The system described here will achieve a higher accuracy than reportedin the above table due to the combination of the inertial guidancesystem that permits accurate changes in position to be determined andthrough multiple GPS readings. In other words, the calculated positionwill converge to the real position over its time. The addition of DGPSwill provide an accuracy improvement of at least a factor of 10, which,with the addition of a sufficient number of DGPS stations in some casesis sufficient without the use of the carrier frequency correction. Afurther refinement where the vehicle becomes its own DGPS stationthrough the placement of infrastructure stations at appropriatelocations on roadways will further significantly enhance the systemaccuracy to the required level.

Multipath is the situation where more than one signal from a satellitecomes to a receiver with one of the signals resulting from a reflectionoff of a building or the ground, for example. Since multipath is afunction of geometry, the system can be designed to eliminate itseffects based on highway surveying and appropriate antenna design.Multipath from other vehicles can also be eliminated since the locationof the other vehicles will be known.

As discussed below. the Wide Area Augmentation System (WAAS) is beinginstalled by the US Government to provide DGPS for airplane landings.The intent is to cover the entire continental U.S. (CONUS). This may beuseful for much of the country for the purposes of this invention.Another alternative would be to use the cellular phone towers, sincethere are so many of them, if they could be programmed to act aspseudolites.

An important feature of DGPS is that the errors from the GPS satelliteschange slowly with time and therefore, only the corrections need be sentto the user from time to time. Using reference receivers separated by25-120 km, accuracies from 10 cm to 1 m are achievable using local areaDGPS which is marginal for RtZF. Alternately, through the placement ofappropriate infrastructure transmitters as described below even betteraccuracies are obtainable.

A type of wide area DGPS (WADGPS) system has been developed spans theentire US continent which provides position RMS accuracy to better than50 cm. This system is described in the Bertiger, et al, “A PrototypeReal-Time Wide Area Differential GPS System,” Proceedings of theNational Technical Meeting, Navigation and Positioning in theInformation Age, Institute of Navigation, Jan. 14-16, 1997 pp. 645-655.A RMS error of 50 cm would be marginally accurate for RtZF. Many of theteachings of this invention especially if the road edge and lanelocation error were much less which could be accomplished using moreaccurate surveying equipment. The OmniSTAR system is another WADGPSsystem that claims 6 cm (1σ) accuracy.

A similar DGPS system which is now being implemented on a nationwidebasis is described in ““DGPS Architecture Based on Separating ErrorComponents, Virtual Reference Stations and FM Subcarrier Broadcast”, byDifferential Corrections Inc., 10121 Miller Ave., Cupertino, Calif.95041. The system described in this paper promises an accuracy on theorder of 10 cm.

Suggested DGPS update rates are usually less than twenty seconds. DGPSremoves common-mode errors, those errors common to both the referenceand remote receivers (not multipath or receiver noise). Errors are moreoften common when receivers are close together (less than 100 km).Differential position accuracies of 1-10 meters are possible with DGPSbased on C/A code SPS signals.

Using the CNET commercial system, 1 foot accuracies are possible if basestations are no more than 30 miles from the vehicle unit. This wouldrequire approximately 1000 base stations to cover CONUS. Alternately,the same accuracy is obtainable if the vehicle can become its ownDGPSsystem every 30 miles as described below.

Unfortunately, the respective error sources mentioned above rapidlydecorrelate as the distances between the reference station and thevehicle increases. Conventional DGPS is the terminology used when theseparation distances are sufficiently small that the errors cancel. Theterms single-reference and multi-reference DGPS are occasionally used inorder to emphasize whether there is a single reference station orwhether there are multiple ones. If it is desired to increase the areaof coverage and, at the same time, to minimize the number of fixedreference receivers, it becomes necessary to model the spatial andtemporal variations of the residual errors. Wide Area Differential GPS(WADGPS) is designed to accomplish this. In addition, funds have nowbeen appropriated for the US Government to deploy a national DGPSsystem.

Pseudolites

Pseudolites are artificial satellite like structures, located on theearth surface, that can be deployed to enhance the accuracy of the DGPSsystem. Such structures could become part of the RtZF™ system.

WAAS

The Wide Area Augmentation System (WAAS) is being deployed to replacethe Instrument Landing System used at airports across the country. TheWAAS system provides an accuracy of from about 1 to 2 meters for thepurpose of aircraft landing. If the vertical position of the vehicle isknown, as would be in the case of automobiles at a known position on aroad, this accuracy can be improved significantly. Thus, for many of thepurposes of this invention, the WAAS can be used, to provide accuratepositioning information for vehicles on roadways. The accuracy of theWAAS is also enhanced by the fact that there is an atomic clock in everyWAAS receiver station that would be available to provide great accuracyusing carrier phase data. With this system sub-meter accuracies arepossible for some locations.

The WAAS is based on a network of approximately 35 ground referencestations. Signals from GPS satellites are received by aircraft receiversas well as by ground reference stations. Each of these referencestations is precisely surveyed, enabling each to determine any error inthe GPS signals being received at its own location. This information isthen passed to a wide area master station. The master station calculatescorrection algorithms and assesses the integrity of the system. Thisdata is then put into a message format and sent to a ground earthstation for uplink to a geostationary communications satellite. Thecorrective information is forwarded to the receiver on board theaircraft, which makes the needed adjustments. The communicationssatellites also act as additional navigation satellites for theaircraft, thus, providing additional navigation signals for positiondetermination.

This system will not meet all of FAA's requirements. For category IIIlandings, the requirement is 1.6-m vertical and horizontal accuracy. Toachieve this, FAA is planning to implement a network of local areadifferential GPS stations that will provide the information to aircraft.This system is referred to as the Local Area Augmentation System (LAAS).

The WAAS system, which consists of a network of earth stations andgeo-synchronous satellites, is currently being funded by the U.S.Government for aircraft landing purposes. Since the number of peoplethat die yearly in automobile accidents greatly exceeds those killed inairplane accidents, there is clearly a greater need for a WAAS typesystem for solving the automobile safety problem using the teachings ofthis invention. Also, the reduction in required highway fundingresulting from the full implementation of this invention would more thenpay for the extension and tailoring of the WAAS to cover the nationshighways.

LAAS

The Local Area Augmented System (LAAS) is also being deployed inaddition to the WAAS system to provide even greater coverage for theareas surrounding major airports. According to Newsletter of theInstitute of Navigation, 1997, “the FAA's schedule for (LAAS) forCategory II and III precision instrument approaches calls fordevelopment of standards by 1998 that will be sufficient to complete aprototype system by 2001. The next step will be to work out standardsfor an operational system to be fielded in about 2005, that could servenationwide up to about 200 runways for Cat II-III approaches.”

In a country like the United States, which has many airfields, a WAAScan serve a large market and is perhaps most effective for the controlof airplane landings. The best way for other countries, with fewerairports, to participate in the emerging field of GPS-based aviationaids may be to build LAAS. In countries with a limited number ofairports, LAAS is not very expensive while the costs of building a WAASto get Category I type accuracy is very expensive. However, with theadded benefit of less highway construction and greater automobilesafety, the added costs for a WAAS system may well be justified for muchof the world.

For the purposes of the RtZF™ system, both the WAAS and LAAS would beuseful but probably insufficient unless the information is used in adifferent mathematical system such as used by the OmniSTAR™ WADGPSsystem. Unlike an airplane, there are many places where it might not bepossible to receive LAAS and WAAS information or even more importantlythe GPS signals themselves with sufficient accuracy and reliability.Initial RtZFT™ systems may therefore rely on the WAAS and LAAS but asthe system develops more toward the goal of zero fatalities, road basedsystems which permit a vehicle to pinpoint its location will bepreferred. However, there is considerable development ongoing in thisfield so that all systems are still candidates for use with RtZF™ systemand the most cost effective will be determined in time.

Carrier Phase Measurements

An extremely accurate form of GPS is Carrier Based Differential GPS.This form of GPS utilizes the 1.575 GHz carrier component of the GPSsignal on which the Pseudo Random Number (PRN) code and the datacomponent are superimposed. Current versions of Carrier BasedDifferential GPS involve generating position determinations based on themeasured phase differences at two different antennas, a base station orpseudolite and the vehicle, for the carrier component of a GPS signal.This technique initially requires determining how many integerwave-lengths of the carrier component exist between the two antennas ata particular point in time. This is called integer ambiguity resolution.A number of approaches currently exist for integer ambiguity resolution.Some examples can be found in U.S. Pat. Nos. 5.583,513 and 5,619,212.Such systems can achieve sub-meter accuracies and, in some cases;accuracies of about 1 cm or less. U.S. Pat. No. 5,477,458 discloses aDGPS system that is accurate to about 5 cm with the base stationslocated on a radius of about 3000 km. With such a system, very few basestations would be required to cover the continental United States. Thissystem still suffers from the availability of accurate signals at thevehicle regardless of its location on the roadway and the location ofsurrounding vehicles and objects. Nevertheless, the principle of usingthe carrier frequency to precisely determine the location of a vehiclecan be used with the highway based systems described below to provideextreme location accuracies. Using the PPS system described below wherea vehicle becomes its own DGPS system, the carrier phase ambiguityproblem also disappears since the number of cycles can be calculated ifthe precise location is known. There is no ambiguity when the vehicle isat the PPS station and that is maintained as long as the lock on asatellite is not lost for more than a few minutes.

Other Aids

There are other sources of information that can be added to increase theaccuracy of position determination, The use of GPS with four satellitesprovides the three dimension location of the vehicle plus time. Of thedimensions, the vertical is the least accurately known, yet, if thevehicle knows where it is on the roadway, the vertical dimension is notonly the least important but it is also already accurately known fromthe roadmap information plus the inertial guidance system.

Another aid is to provide markers along side the roadway which can beeither visual, passive or active transponders, reflectors, or a varietyof other technologies, which have the property that as a vehicle passesthe marker it can determine the identity of the marker and from adatabase it can determine the exact location of the marker. If three ormore of such markers are placed along side of the roadway, a passingvehicle can determine its exact location by triangulation. Although itmay be impractical to initially place such markers along all roadways,it would be reasonable to place them in particularly congested areas orplaces where it is known that a view of one or more of the GP Ssatellites is blocked. A variation of this concept will be discussedbelow.

Although initially it is preferred to use the GPS navigationalsatellites as the base technology, the invention is not limited therebyand contemplates using all methods by which the location of the vehiclecan be accurately determined relative to the earth surface. The locationof the roadway boundaries and the location of other vehicles relative tothe earth surface are also to be determined and all relevant informationused in a control system to substantially reduce and eventuallyeliminate vehicle accidents. Only time and continued system developmentwill determine the mix of technologies that provide the most costeffective solution. All forms of information and methods ofcommunication to the vehicle are contemplated including directcommunication with stationary and moving satellites, communication withfixed earth-based stations using infrared, optical, radar, radio andother segments of the electromagnetic spectrum. Some additional examplesfollow:

A pseudo-GPS can be delivered from cell phone stations, in place of orin addition to satellites. In fact, the precise location of a cell phonetower need not initially be known. If it monitors the GPS satellitesover a sufficiently long time period, the location can be determined asthe calculated location statistically converges to the exact location.Thus, every cell phone tower could become an accurate DGPS base stationfor very little cost. DGPS corrections can be communicated to a vehiclevia FM radio via a sub-carrier frequency for example. An infrared orradar transmitter along the highway can transmit road boundary locationinformation. A CD-ROM or other portable mass storage can be used at thebeginning of a controlled highway to provide road boundary informationto the vehicle. Finally, it is contemplated that eventually a satellitewill broadcast periodically, perhaps every five minutes, a table ofdates covering the entire CONUS that provides the latest update date ofeach map segment. If a particular vehicle does not have the latestinformation for a particular region where it is operating, it will beable to use its cell phone to call and retrieve such road maps perhapsthrough the Internet. Emergency information would also be handled in asimilar manner so that if a tree fell across the highway, for example,all nearby vehicles would be notified.

Other Location Fixing Systems

It is expected, especially initially, that there will be many holes inthe DGPS or GPS and their various implementations that will leave thevehicle without an accurate means of determining its location. Theinertial navigation system described below will help in filling theseholes but its accuracy is limited to a time period significantly lessthan an hour and a distance of less than 50 miles before it needscorrecting. That may not be sufficient to cover the period between DGPSavailability. It is therefore contemplated that the RtZF system willalso make use of low cost systems located along the roadways that permita vehicle to accurately determine its location. One example of such asystem would be to use a group of three Micropower Impulse Radar (MIR)units such as developed by Lawrence Livermore Laboratory.

A MIR operates on very low power and periodically transmits a very shortspread spectrum radar pulse. The estimated cost of a MIR is less than$10 even in small quantities. If three such MIR transmitters, 151, 152and 153, as shown in FIG. 11, are placed along the highway and triggeredsimultaneously or with a known delay, and if a vehicle has anappropriate receiver system, the time of arrival of the pulses can bedetermined and thus the location of the vehicle relative to thetransmitters determined. The exact location of the point where all threepulses arrive simultaneously would be the point that is equidistant fromthe three transmitters and would be located on the map information. Onlythree devices are required since only two dimensions need to bedetermined since it is assumed that the vehicle in on the road and thusthe vertical position is known, otherwise four MIRs would be required.Thus it would not even be necessary to have the signals containidentification information since the vehicle would not be so far off inits position determination system to confuse different locations. Bythis method, the vehicle would know exactly where it was whenever itapproached and passed such a triple-MIR installation. The MIR triad PPSor equivalent could also have a GPS receiver and thereby determine itsexact location over time as described above for cell phone towers. Afterthe location has been determined, the GPS receiver can be removed. Inthis case, the MIR triad PPS or equivalent could be placed at will andthey could transmit their exact location to the passing vehicles. Analternate method would be to leave the GPS receiver with the PPS time ofarrival of the GPS data from each satellite so that the passing vehiclesthat do not go sufficiently close to the PPS can still get an exactlocation fix. A similar system using RFID tags is discussed below.

Naturally, several such readings and position determinations can be madewith one approach to the MIR installation, the vehicle need not waituntil they all arrive simultaneously. Also the system can be designed sothat the signals never arrive at the same time and still provide thesame accuracy as long as there is a sufficiently accurate clock on boardthe vehicle. One way at looking at FIG. 11 is that transmitters 151 and152 fix the lateral position of the vehicle while transmitters 151 and153 fix the location of the vehicle longitudinally. The threetransmitters 151,152,153 need not be along the edges on one lane butcould span multiple lanes and they need not be at ground level but couldbe placed sufficiently in the air so that passing trucks would not blockthe path of the radiation from an automobile, Particularly in congestedareas, it might be desirable to code the pulses and to provide more thanthree transmitters to further protect against signal blockage ormultipath.

The power requirements for the MIR transmitters are sufficiently lowthat a simple photoelectric cell array can provide sufficient power formost if not all CONUS locations. With this exact location information,the vehicle can become its own DGPS station and can determine thecorrections necessary for the GPS. It can also determine the integerambiguity problem and thereby know the exact number of wave lengthsbetween the vehicle and the satellites or between the vehicle and theMIR station.

MIR is one of several technologies that can be used to provide preciselocation determination. Others include the use of an RFID tag that isdesigned in cooperation with its interrogator to provide a distance tothe tag measurement and radar or other reflectors where the time offlight can be measured.

Once a vehicle passes a Precise Positioning Station (PPS) such as theMIR triad described above, the vehicle can communicate this informationto surrounding vehicles. If the separation distance between twocommunicating vehicles can also be determined by the time-of-flightmethod, then the vehicle that has just passed the triad can, in effect,become a satellite equivalent or moving pseudolite. Finally, if manyvehicles are communicating their positions to many other vehicles alongwith an accuracy of position assessment, each vehicle can use thisinformation along with the measured separation distances to improve theaccuracy that its position is known. In this manner, as the number ofsuch vehicles increases the accuracy of the whole system increases untilan extremely accurate positioning system for all vehicles results. Sucha system, since it combines many sources of position information, istolerant of the failure of any one or even several such sources. Thus,the RtZF™ system becomes analogous to the Internet in that it can't beshut down and the goal of perfection is approached. Some of the problemsassociated with this concept will be discussed in more detail below.

Inertial Navigation System

In many cases, especially before the system implementation becomesmature and the complete infrastructure is in place, there will be timeswhen a particular vehicle system is not operational. This could be dueto obstructions hiding a clear view of a sufficient number of GPSsatellites, such as when a vehicle enters a tunnel. It could also be dueto a lack of road boundary information, due to construction or the factthat the road has not been surveyed and the information recorded andmade available to the vehicle, or a variety of other causes. It iscontemplated, therefore, that each equipped vehicle will contain awarning light that warns the driver when he or she is at a positionwhere the system is not operational. If this occurs on one of theespecially designated highway lanes, the vehicle speed will be reduceduntil the system again becomes operational.

When the system is non-operational for a short distance, the vehiclewill still accurately know its position if there is, in addition, one ormore laser gyroscopes, micromachined angular rate sensors or equivalent,and one or more accelerometers that together are referred to as anInertial Navigation System (INS). Generally, such an INS will have threegyroscopes and three accelerometers.

As more sensors which are capable of providing information on thevehicle position, velocity and acceleration are added onto the vehicle,the system can become sufficiently complicated as to require a neuralnetwork, or neural-fuzzy, system to permit the optimum usage of theavailable information. This becomes even more important when informationfrom outside the vehicle other than the GPS related systems becomes moreavailable. For example, a vehicle may be able to communicate with othervehicles that have similar systems and learn their estimated location.If the vehicle can independently measure the position of the othervehicle, for example through the use of the scanning impulse laser radarsystem described below, and thereby determine the relative position ofthe two or more vehicles, a further improvement of the position can bedetermined for all such vehicles. Adding all such additional informationinto the system would probably require a computational method such asneural networks or a combination of a neural network and a fuzzy logicsystem.

Conclusion—How Used

One way to imagine the system operation is to consider each car androadway edge to behave as if it had a surrounding “force field” thatwould prevent it from crashing into another vehicle or an obstacle alongthe roadway. A vehicle operator would be prevented from causing his orher vehicle to leave its assigned corridor. This is accomplished with acontrol system that controls the steering, acceleration and perhaps thevehicle brakes based on its knowledge of the location of the vehicle,highway boundaries and other nearby vehicles. In a preferredimplementation, the location of the vehicle is determined by first usingthe GPS L1 signal to determine its location within approximately 100meters. Then using DGPS and corrections which are broadcast whether byFM or downloaded from geo-synchronous or Low Earth Orbiting (LEO)satellites or obtained from road based transmitters to determine itslocation within less than about 10 centimeters. Finally the use of a MIRor similar system periodically permits the vehicle to determine itsexact location and thereby determine the GPS corrections, eliminate thecarrier cycle ambiguity and set the INS system. If this is still notsufficient, then the phase of the carrier frequency provides therequired location information to less than a few centimeters. Deadreckoning, using vehicle speed, steering angle and tire rotationinformation and/or inertial guidance, can be used to fill in the gaps.Where satellites are out of view, pseudolites, or other systems, areplaced along the highway. A pulsed scanning infrared laser radar system,or an equivalent system, is used for obstacle detection. Communicationto other vehicles is by short distance radio or by spread spectrum timedomain pulse radar as described by Time Domain Incorporated.

One problem which will require addressing as the system becomes matureis temporary blockage of a satellite by large trucks or other movableobjects. whose location cannot be foreseen by the system designers.Another concern is to prevent vehicle owners from placing items on thevehicle exterior that block the GPS and communication antennas.

Communication with Other Vehicles—Collision Avoidance

MIR might also be used for vehicle to vehicle communication except thatit is line of sight. An advantage is that we can know when a particularvehicle will respond by range gating. Also, the short time oftransmission permits many vehicles to communicate at the same time.

Description—Requirements

The communication between vehicles for collision avoidance purposescannot solely be based on line-of-sight technologies as this is notsufficient since vehicles which are out of sight can still causeaccidents. On the other hand, vehicles that are a mile away from oneanother but still in sight, need not be part of the communicationsystem. Messages sent by each vehicle, in accordance with an embodimentof the invention, would contain information indicating exactly where itis located and perhaps information as to what type of vehicle it is. Thetype of vehicle can include emergency vehicles, construction vehicles,trucks classified by size and weight, automobiles, and oversizedvehicles. The subject vehicle can therefore eliminate all of thosevehicles that are not potential threats, even if such vehicles are veryclose, but on the other side of the highway barrier.

The use of an Ethernet protocol will satisfy the needs of the network,consisting of all threatening vehicles in the vicinity of the subjectvehicle. Alternately, a network where the subject vehicle transmits amessage to a particular vehicle and waits for a response could be used.From the response time, the relative position of other vehicles can beascertained which provides one more method of position determination.Thus, the more vehicles that are on the road with the equipped system,the greater accuracy of the overall system and the safer the systembecomes, as described above.

To prevent accidents caused by a vehicle leaving the road surface andimpacting a roadside obstacle requires only an accurate knowledge of theposition of the vehicle and the road boundaries. To prevent collisionswith other vehicles requires that the position of all nearby automobilesmust be updated continuously. But just knowing the position of athreatening vehicle is insufficient. The velocity, size and orientationof the vehicle are also important in determining what defensive actionor reaction may be required. Once all vehicles are equipped with thesystem of this invention, the communication of all relevant informationwill take place via a communication link, e.g., a radio link. Inaddition to signaling its absolute position, each vehicle will send amessage identifying the approximate mass, velocity, orientation, andother relevant information. This has the added benefit that emergencyvehicles can make themselves known to all vehicles in their vicinity andall such vehicles can then take appropriate action. The same system canalso be used to relay accident or other hazard information from vehicleto vehicle.

U.S. Pat. No. 5,128,669 to Dabbs provides for 2-way communication andaddressing messages to specific vehicles. This is unnecessary and thecommunications can be general since the amount of information that isunique to one vehicle is small. A method of handing bidirectionalcommunication is. disclosed in U.S. Pat. No. 5,506,584 to Boles.

Preferred System

One preferred method of communication between vehicles uses that portionof the electromagnetic spectrum that permits only line of sightcommunication. In this manner, only those vehicles that are in view cancommunicate. In most cases. a collision can only occur between vehiclesthat can see each other. This system has the advantage that the“communications network” only contains nearby vehicles. This wouldrequire that when a truck. for example, blocks another stalled vehiclethat the information from the stalled vehicle be transmitted via thetruck to a following vehicle. An improvement in this system would use arotating aperture that would only allow communication from a limitedangle at a time further reducing the chance for multiple messages tointerfere with each other. Each vehicle transmits at all angles butreceives at only one angle at a time. This has the additional advantageof confirming at least the direction of the transmitting vehicle. Aninfrared rotating receiver can be looked at as similar to the human eye.That is, it is sensitive to radiation from a range of directions andthen focuses in on the particular direction, one at a time, from whichthe radiation is coming. It does not have to scan continuously. In fact,the same transmitter which transmits 360 degrees could also receive from360 degrees with the scanning accomplished using software.

An alternate preferred method is to use short distance radiocommunication so that a vehicle can receive position information fromall nearby vehicles such as the DS/SS system. The location informationreceived from each vehicle can then be used to eliminate it from furthermonitoring if it is found to be on a different roadway or not in apotential path of the subject vehicle.

Many communications schemes have been proposed for inter-vehicle andvehicle-to-road communication. At this, time, a suggested approachutilizes DS/SS communications in the 2.4 GHz INS band. Experiments haveshown that communications are 100 percent accurate at distances up to200 meters. At a closing velocity of 200 KPH, at 0.5 g deceleration, itrequires 30 meters for a vehicle to stop. Thus, communication accurateto 200 meters is sufficient to cover all vehicles that are threateningto a particular vehicle.

A related method would be to use a MIR system in a communications mode.Since the width of the pulses typically used by MIR is less than ananosecond, many vehicles can transmit simultaneously without fear ofinterference.

With either system, other than the MIR system, the potential exists thatmore than one vehicle will attempt to send a communication at the sametime and there will then be a ‘data collision’. If all of thecommunicating vehicles are considered as being part of a local areanetwork, the standard Ethernet protocol can be used to solve thisproblem. In that protocol, when a data collision occurs, each of thetransmitting vehicles which was transmitting at the time of the datacollision would be notified that a data collision had occurred and thatthey should retransmit their message at a random time later. Whenseveral vehicles are in the vicinity and there is the possibility ofcollisions of the data, each vehicle can retain the coordinates lastreceived from the surrounding vehicles as well as their velocities andpredict their new locations even though some data was lost.

If a line of sight system is used, an infrared or MIR system would begood choices. In the infrared case, and if an infrared system were alsoused to interrogate the environment for non-equipped vehicles,pedestrians, animals etc., as discussed below, both systems could usesome of the same hardware.

If point-to-point communication can be established between vehicles,such as described in U.S. Pat. No. 5,528,391 to Elrod, then the need fora collision detection system like Ethernet would not be required. If thereceiver on a vehicle, for example, only has to listen to one senderfrom one other vehicle at a time, then the bandwidth can be considerablyhigher since there will not be any interruption.

When two vehicles are communicating their positions to each other, it ispossible through the use of range gating or the sending of a “clear tosend signal” and timing the response to determine the separation of thevehicles. This assumes that the properties of the path between thevehicles is known which would be the case if the vehicles are withinview of each other. If, on the other hand, there is a row of trees, forexample, between the two vehicles, a false distance measurement would beobtained if the radio waves pass through a tree. If the communicationfrequency is low enough that it can pass through a tree in the aboveexample, it will be delayed. If it is a much higher frequency such thatis blocked by the tree then it still might reach the second vehiclethrough a multi-path. Thus, in both cases an undetectable range errorresults. If a range of frequencies is sent, as in a spread spectrumpulse, and the first arriving pulse contains all of the sent frequenciesthen it is likely that the two vehicles are in view of each other andthe range calculation is accurate. If any of the frequencies are delayedthen the range calculation can be considered inaccurate and should beignored. Once again, for range purposes, the results of manytransmissions and receptions can be used to improve the separationdistance accuracy calculation. Alternate methods for determining rangecan make use of radar reflections, RFID tags etc.

Enhancements

In the accident avoidance system of the present invention, theinformation indicative of a collision could come from a vehicle that isquite far away from the closest vehicles to the subject vehicle. This isa substantial improvement over the prior art collision avoidancesystems, which can only react to a few vehicles in the immediatevicinity. The system described herein also permits better simultaneoustracking of several vehicles. For example, if there is a pileup ofvehicles down the highway then this information can be transmitted tocontrol other vehicles that are still a significant distance from theaccident. This case cannot be handled by prior art systems. Thus, thesystem described here has the potential to be part of the U.S. Pat. No.5,572,428 to Ishida, for example.

The network analogy, can be extended if each vehicle receives andretransmits all received data as a single block of data. In this way,each vehicle is assured in getting all of the relevant information evenif it gets it from many sources. Even with many vehicles, the amount ofdata being transmitted is small relative to the bandwidth of theinfrared optical or radio technologies. Naturally, in some particularcases, a receiver and retransmitter can be part of the highwayinfrastructure. Such a case might be on a hairpin curve in the mountainswhere the oncoming traffic is not visible.

In some cases, it may be necessary for one vehicle to communicate withanother to determine which evasive action each should take. This couldoccur in a multiple vehicle situation when one car has gone out ofcontrol due to a blowout, for example. In such cases, one vehicle mayhave to tell the other vehicle what evasive actions it is planning. Theother vehicle can then calculate whether it can avoid a collision basedof the planned evasive action of the first vehicle and if not it caninform the first vehicle that it must change its evasive plans. Theother vehicle would also inform the first vehicle as to what evasiveaction it is planning. Several vehicles communicating in this manner candetermine the best paths for all vehicles to take to minimize the dangerto all vehicles.

If a vehicle is stuck in a corridor and wishes to change lanes in heavytraffic, the operator's intention can be signaled by the operatoractivating the turn signal. This could send a message to other vehiclesto slow down and let the signaling vehicle change lanes. This would beparticularly helpful in an alternate merge situation.

Communication with Highway—Maps

Statement of the Problem

The initial maps showing roadway lane and boundary location for theCONUS should preferably be installed within the vehicle at the time ofmanufacture. The vehicle thereafter would check on a section by sectionbasis whether it had the latest update information for the particularand surrounding locations where it is being operated. One method ofverifying this information would be achieved if a satellite periodicallybroadcasts the latest date and time or version that each segment hadbeen most recently updated. This matrix would amount to a smalltransmission requiring perhaps from a few seconds to one minute ofairtime. Any additional emergency information could also be broadcast inbetween the periodic transmissions to cover accidents, trees fallingonto roads etc. If the periodic transmission were to occur every fiveminutes and if the motion of a vehicle were somewhat restricted until ithad received a periodic transmission, the safety of the system can beassured. If the vehicle finds that it does not have the latest mapinformation, the cell phone in the vehicle can be used to log onto theInternet, for example, and the missing data downloaded. An alternate isfor the LEOs, or other satellites, to broadcast the map correctionsdirectly.

It is also possible that the map data could be off loaded from atransmitter on the highway itself. In that manner, the vehicles wouldonly obtain that map information which it needed and the map informationwould always be up to the minute. As a minimum, temporal datacommunication stations can be placed before highway sections that areundergoing construction or where a recent blockage has occurred andwhere the maps have not yet been updated. Such an emergency datatransfer would be signaled to all approaching vehicles to reduce speedand travel with care. Naturally such information could also containmaximum and minimum speed information which would limit the velocity ofvehicles in the area.

There is other information that would be particularly useful to avehicle operator or control system, including in particular the weatherconditions especially at the road surface. Such information could beobtained by road sensors and then transmitted to all vehicles in thearea by a permanently installed system. Alternately, there have beenrecent studies that show that icing conditions on road surfaces, forexample, can be accurately predicted by local meteorological stationsand broadcast to vehicles in the area. If such a system is not present,then, the best place to measure road friction is at the road surface andnot on the vehicle. The vehicle requires advance information of an icingcondition in order to have time to adjust its speed or take otherevasive action. The same road based or local meteorological transmittersystem could be used to warn the operators of traffic conditions,construction delays etc. and to set the local speed limit.

Maps

All information regarding the road, both temporary and permanent, shouldbe part of the map database, including speed limits, presence of guardrails, width of each lane, width of the highway, width of the shoulder,character of the land beyond the roadway, existence of poles or treesand other roadside objects, exactly where the precise position locationapparatus is located, etc. The speed limit associated with particularlocations on the maps should be coded in such a way that the speedslimit can depend upon the time of day and the weather conditions. Inother words, the speed limit is a variable that will change from time totime depending on conditions. It is contemplated that there will be adisplay for various map information present which will always be in viewfor the passenger and for the driver at least when the vehicle isoperating under automatic control. Additional user information can thusalso be displayed such as traffic conditions, weather conditions,advertisements, locations of restaurants and gas stations, etc.

A map showing the location of road and lane boundaries can be easilygenerated using a specially equipped survey vehicle that has the mostaccurate position measurement system available. In some cases, it mightbe necessary to set up one or more temporary local DGPS base stations inorder to permit the survey vehicle to know its position within a fewcentimeters. The vehicle would drive down the roadway while operators,using specially designed equipment, sight the road edges and lanes. Thiswould probably best be done with laser pointers and cameras. Transducersassociated with the pointing apparatus record the angle of the apparatusand then by triangulation determine the distance of the road edge orlane marking from the survey vehicle. Since the vehicle's position wouldbe accurately known, the boundaries and lane markings can be accuratelydetermined. It is anticipated that the mapping activity would take placecontinuously such that all roads in a particular state would beperiodically remapped in order to pickup up any changes which weremissed by other monitoring systems and to improve the reliability of themaps by minimizing the chance for human error. Any roadway changes thatwere discovered would trigger an investigation as to why they were notrecorded earlier thus adding feedback to the mapping part of theprocess.

The above-described method depends on human skill and attention and thusis likely to result in many errors. A preferred approach is to carefullyphotograph the edge of the road and use the laser pointers to determinethe location of the road lines relative to the pointers and to determinethe slope of the roadway through triangulation. In this case severallaser pointers would be used emanating from above, below and to thesides of the camera. The reduction of the data is then done later usingequipment that can automatically pick out the lane markings and thereflected spots from the laser pointers. One aid to the mapping processis to place chemicals in the line paint that could be identified by thecomputer software when the camera output is digitized. This may requirethe illumination of the area being photographed by an infrared orultraviolet light, for example.

In some cases where the roadway is straight, the survey vehicle couldtravel at moderate speed while obtaining the boundary and lane locationinformation. In other cases, where the road in turning rapidly, morereadings would be required per mile and the survey vehicle would need totravel more slowly. In any case, the required road information can beacquired semi-automatically with the survey vehicle traveling at amoderate speed. Thus, the mapping of a particular road would not requiresignificant time or resources. It is contemplated that a few such surveyvehicles could map all of the interstate highways in the United Statesin less than one year.

The mapping effort could be supplemented and cross-checked though theuse of accurate detailed digital photogrammetic systems which, forexample, can determine the road altitude with an accuracy to <50 cm.Efforts are underway to map the earth with 1-meter accuracy. Thegenerated maps could be used to check the accuracy of theroad-determined maps.

Another improvement that can be added to the system based on the maps isto use a heads up display for in-vehicle signage. As the vehicle travelsdown the road, the contents of road side signs can be displayed on aheads up display, providing such a display is available in the vehicle,or on a specially installed LCD display. This is based on the inclusionin the map database the contents of all highway signs. A furtherimprovement would be to include signs having varying messages whichwould require that the message be transmitted by the sign to the vehicleand received and processed for in vehicle display.

As the roadway is being mapped, the availability of GPS satellite view,and the presence of multipath reflections from fixed structures can alsobe determined. This information can then be used to determine theadvisability of locating a local precise location system, or otherinfrastructure at a particular spot on the roadway. Cars can also beused as probes for this process and for continuous improvement to checkthe validity of the maps and report any errors.

Multipath is the situation where more than one signal from a satellitecomes to a receiver with one of the signals resulting from a reflectionoff of a building or the ground, for example. Since multipath is afunction of geometry, the system can be designed to eliminate itseffects based on highway surveying and appropriate antenna design.Multipath from other vehicles can also be eliminated since the locationof the other vehicles will be known.

Privacy

People do not necessarily want the government to know where they aregoing and therefore will not want information to be transmitted that canidentify the vehicle. The importance of this issue may be overestimated.Most people will not object to this minor infraction if they can get totheir destination more efficiently and safely.

On the other hand, it has been estimated that there are 100,000 vehicleson the road, many of them stolen, where the operators do not want thevehicle to be identified. If an identification process that positivelyidentifies the vehicle were made part of this system, it could thus cutdown on vehicle theft. Alternately, thieves might attempt to disconnectthe system thereby defeating the full implementation of the system andthus increasing the danger on the roadways and defeating the RTZFobjective. The state of the system would therefore need to beself-diagnosed and system readiness must be a condition for entry ontothe restricted lanes.

Sensing of Non-RtZF Equipped Objects

Problem Statement

Vehicles with the RtZF™ system in accordance with the invention mustalso be able to detect those vehicles that do not have the system aswell as pedestrians, animals, bicyclists, and other hazards that maycross the path of the equipped vehicle.

Prior Art

Although, there appears not to be any significant prior art involving avehicle communicating safety information to another vehicle on theroadway, several patents discuss methods of determining that a collisionmight take place using infrared and radar. U.S. Pat. No. 5,249,128 toMarkandey et al., for example, discusses methods of using infrared todetermine the distance to a vehicle in front and U.S. Pat. No. 5,506,584to Boles describes a radar-based system. Both systems suffer from a highfalse alarm rate and could be substantially improved if a patternrecognition system such as neural networks were used.

Description

Systems based on radar have suffered from the problem of being able tosufficiently resolve the images which are returned to be able toidentify the other vehicles, bridges, etc. One method used for adaptivecruise control systems is to ignore everything that is not moving. This,of course, leads to accidents if this were used with the instantinvention. The problem stems from the resolution achievable with radarunless the antenna is made very large. Since this is impractical for usewith automobiles, only minimal collision avoidance can be obtained usingradar.

Optical systems can provide the proper resolution but may requireillumination with a bright light or laser. If the laser is in theoptical range, there is a danger of causing eye damage to pedestrians orvehicle operators. As a minimum, it will be distracting and annoying toother vehicle operators. A laser operating in the infrared part of theelectromagnetic spectrum avoids the eve danger problem, provided thefrequency is sufficiently far from the visible, and, since it will notbe seen, it will not be annoying. Infrared also has the properresolution so that pattern recognition technologies can be employed torecognize various objects, such as vehicles, in the reflected image.Infrared has another advantage from the object recognition perspective.All objects radiate and reflect infrared. The hot engine or tires of amoving vehicle in particular are recognizable signals. Thus, if the areaaround a vehicle is observed with both passive and active infrared, moreinformation can be obtained than from radar, for example. Infrared isless attenuated by fog than optical frequencies, although it is not asgood as radar. Infrared is also attenuated by snow but at the properfrequencies it has about five times the range of human sight.

An example of such an instrument is made by Sumitomo Electric and issufficient for the purpose here. The Sumitomo product has beendemonstrated to detect leaves of a tree at a distance of about 300meters. The product operates at a 1.5 micron wavelength.

This brings up a philosophical discussion about the trade-offs betweenradar with greater range and infrared laser radar with more limitedrange but greater resolution. At what point should driving during badweather conditions be prohibited? If the goal of zero fatalities is tobe realized, then people should not be permitted to operate theirvehicles during dangerous weather conditions. This may require closingroads and highways prior to the start of such conditions. Under such apolicy, a system which accurately returns images of obstacles on theroadway that are two to five times the visual distance should beadequate. In such a case, radar would not be necessary.

Laser Radar Scanning System

The digital map can be used to define the field that the laser radarscanner will interrogate. The laser radar scanner will returninformation as to distance to an object in the scanned field. This willcover all objects that are on or adjacent to the highway. The laserpulse can be a pixel that is one inch in diameter at 100 feet, forexample. The scanner must scan the entire road at such a speed that themotion of the car can be considered insignificant. Alternately, aseparate aiming system that operates at a much lower speed, but at aspeed to permit compensation for the car angle changes. Such an aimingsystem is also necessary due to the fact that the road curves up anddown. Therefore two scanning methods, one a slow, but for large anglemotion and the other fast but for small angles may be required. Thelarge angular system requires a motor drive while the small angularsystem can be accomplished through the use of an acoustic wave system,such as Lithium Niobate (LiNbO₃), which is used to drive a crystal whichhas a large refractive index such as Tellurium dioxide.

Alternately, two systems can be used, a radar system for interrogatinglarge areas and a laser radar for imaging small areas. Either or bothsystems can be range gated.

The laser radar scanner can be set up in conjunction with a range gateso that once it finds a object the range can be narrowed so that onlythat object and other objects at the same range, 65 to 75 feet forexample, are allowed to pass to the receiver. In this way, an image of avehicle can be separated from the rest of the scene for identificationby pattern recognition software. Once the image of the particular objecthas been captured, the range gate is broadened, to about 20 to 500 feetfor example, and the process repeated for another object. In thismanner, all objects in the field of interest to the vehicle can beseparated and individually imaged and identified. The field of interest,of course, is the field where all objects with which the vehicle canpotentially collide reside. Particular known and mapped features on thehighway can be used as aids to the scanning system so that the pitch andperhaps roll angles of the vehicle can be taken into account.

Prior to the time that all vehicles are equipped with the RtZF systemdescribed above, roadways will consist of a mix of vehicles. In thisperiod, it will not be possible to totally eliminate accidents. It willbe possible to minimize the probability of having an accident however,if a laser radar system similar to that described in Shaw (U.S. Pat. No.5,529,138) with some significant modifications is used. It is correctlyperceived by Shaw that the dimensions of a radar beam are too large topermit distinguishing various objects which may be on the roadway in thepath of the instant vehicle. Laser radar provides the necessaryresolution that is not provided by radar. Laser radar as used in thepresent invention however would acquire significantly more data thananticipated by Shaw. Sufficient data in fact would be attained to permitthe acquisition of a 3-dimensional image of all objects in the field ofview. The X and Y dimensions of such objects would, of course, bedetermined knowing the angular orientation of the laser radar beam. Thelongitudinal or Z dimension would be obtained by the time-of-flight ofthe laser beam to a particular point on the object and reflected back tothe detector or by phase methods.

At least two methods are available for resolving the longitudinaldimension for each of the pixels in the image. In one method, a laserradar pulse having a pulse width of one nanosecond could be transmittedtoward the area of interest and as soon as the reflection was receivedand the time-of-flight determined, a new pulse would be sent at aslightly different angular orientation. The laser, therefore, would beacting as a scanner covering the field of interest. A single detectorcould then be used since it would know which pixel was beingilluminated. The distance to the reflection point could be determinedbat time-of-flight thus giving the longitudinal distance to all pointsin view on the object.

Alternately, the entire area of interest can be illuminated and an imagefocused on a CCD or CMOS array. By checking the time-of-flight to eachpixel, one at a time, the distance to that point on the vehicle would bedetermined. A variation of this would be to use a garnet crystal as apixel shutter and only a single detector. In this case, the garnetcrystal would permit the illumination to pass through one pixel at atime through to a detector.

Other methods of associating a distance to a particular reflectionpoint, of course, can now be conceived by those skilled in the art. Inthe laser scanning cases, the total power required of the laser issignificantly less than in the area of illuminated design. However, theability to correctly change the direction of the laser beam in asufficiently short period of time complicates the scanning design. Thesystem would work approximately as follows: The entire area in front ofthe instant vehicle, perhaps as much as a full 180 degree arc in thehorizontal plane would be scanned for objects using either radar orlaser radar. Once one or more objects had been located, the scanningrange would be severely limited to basically cover that particularobject and some surrounding space using laser radar. Based on the rangeto that object, a range gate can be used to eliminate all background andperhaps interference from other objects. In this manner, a very clearpicture or image of the object of interest can be obtained as well asits location and, through the use of a neural network pattern ofrecognition system, the identity of the object can be ascertained as towhether it is a sign, a truck, an automobile or other object. Theidentification of the object will permit an estimate to be made of theobject's mass and thus the severity of any potential collision.

Once a pending collision is identified, this information can be madeavailable to the driver and if the driver ceases to heed the warning,control of the vehicle could be taken from him or her by the system. Theactual usurpation of vehicle control, however, is unlikely initiallysince there are many situations on the highway where the potential for acollision cannot be accurately ascertained. Consequently, this systemcan be thought of as an interim solution until all vehicles have theRtZF system described above.

To use the laser radar in a scanning mode requires some means ofchanging the direction of the emitted pulses of light. One method ofusing a ultrasonic wave to change the diffraction angle of a Telluriumdioxide crystal as disclosed above. This can also be done in a varietyof other ways such as through the use of a spinning mirror, such as iscommon with laser scanners and printers. This mirror would control thehorizontal scanning, for example, with the vertical scanning controlledthough a stepping motor. Alternately, one or more piezoelectricmaterials can be used to cause the laser radar transmitter to rotateabout a pivot point. A rotating system, such as described in Shaw is theleast desirable of the available methods due to the difficult,y inobtaining a good electrical connection between the laser and the vehiclewhile the laser is spinning at a very high angular velocity. Anotherpromising technology is to use MEMS mirrors to deflect the laser beam.

Although the system described above is intended for collision avoidanceor at least the notification of a potential collision, when the roadwayis populated by vehicles having the RtZF™ system and vehicles which donot, its use is still desirable after all vehicles are properlyequipped. It can also be used to search for animals or other objectswhich may be on or crossing the highway, a box dropping off of a truckfor example, a person crossing the road who is not paying attention totraffic. Naturally motorcycles, bicycles, and other vehicles can also bemonitored.

One significant problem with all previous collision avoidance systemswhich use radar or laser radar systems to predict impacts with vehicles,is the inability to known whether the vehicle that is being interrogatedis located on the highway or is off the road. In the system of thepresent invention, the location of the road at any distance ahead of thevehicle would be known precisely from the sub-meter accuracy maps, sothat the scanning system can ignore, for example, all vehicles on laneswhere there is a physical barrier separating the lanes from the lane onwhich the subject vehicle is traveling. This, of course, is a commonsituation on super highways. Similarly, a parked car on the side of thecar would not be confused with a parked car that is in the lane oftravel of the subject vehicle when the road is curving. This permits thesubject invention to be used for automatic cruise control. In contrastwith radar systems, it does not require that vehicles in the path of thesubject vehicle to be moving, so that high speed impacts into stalledtraffic can be avoided.

If a system with a broader beam to illuminate a larger area on the roadin front of the subject vehicle is used, with the subsequent focusing ofthis image onto a CCD or CMOS array, this has an advantage of permittinga comparison of the passive infrared signal and the reflection of thelaser radar active infrared. Metal objects, for example appear cold topassive infrared. This permits another parameter to be used todifferentiate metallic objects from non-metallic objects such as foliageor animals such as deer. The breadth of the beam can be controlled andthereby a particular object can be accurately illuminated. With thissystem, the speed with which the beam steering is accomplished can bemuch slower. Naturally, both systems can be combined into the maximumamount of information to be available to the system.

Through the use of range gating, objects can be relatively isolated fromthe environment surrounding it other than for the section of highwaywhich is at the same distance. For many cases, a properly trained neuralnetwork can use this data and identify the objects. An alternateapproach is to use the Fourier transform of the scene as input to neuralnetwork. The advantages of this latter approach are that the particularlocation of the vehicle in the image is not critical for identification.

In the future, when the system can take control of the vehicle, it willbe possible to have much higher speed travel. In such cases all vehicleson the controlled roadway will need to have the RtZF™ system asdescribed above. Fourier transforms of the objects of interest can bedone optically though the use of a diffraction system. The Fouriertransform of the scene can then be compared with the library of theFourier transforms of all potential objects and, through a system usedin military target recognition, multiple objects can be recognized andthe system then focused onto one at time to determine the degree ofthreat that it poses.

ITS+Adaptive Cruise Control

Problem—Traffic Congestion

The world is experiencing an unacceptable growth in traffic congestionand attention is increasingly turning to smart highway systems to solvethe problem. It has been estimated that approximately $240 billion willbe spent on smart highways over the next 20 years. All of theinitiatives currently being considered involve a combination ofvehicle-mounted sensors and sensors and other apparatus installed in oron the roadway. Such systems are expensive to install, difficult andexpensive to maintain and will thus only be used on major highways, ifat all. Although there will be some safety benefit from such systems, itwill be limited to the highways which have the system and perhaps toonly a limited number of lanes.

The RtZF™ system in accordance with the invention eliminates theshortcomings of the prior art by providing a system that does notrequire modifications to the highway. The information as to the locationof the highway is determined, as discussed above, by mapping the edgesof the roadway and the edges of the lanes of the roadway using a processwhereby the major roads of the entire country can be mapped at very lowcost. Thus, the system has the capability of reducing congestion as wellas saving lives on all major roads, not just those which have beenselected as high-speed guided lanes.

Description

According to U.S. Pat. No. 5,506,584 the stated goals of the US DOT IVHSsystem are:

improving the safety of surface transportation

increasing the capacity and operational efficiency of the surfacetransportation system

enhancing personal mobility and the convenience and comfort of thesurface transportation system

reducing the environmental and energy impacts of the surfacetransportation system

The RtZF™ system in accordance with the present invention satisfies allof these goals at a small fraction of the cost of prior art systems. Thesafety benefits have been discussed above. The capacity increase isachieved by confining vehicles to corridors where they are thenpermitted to travel at higher speeds. This can be achieved immediatelywhere carrier phase DGPS is available or with the implementation of thehighway located precise location systems as shown in FIG. 11. Animprovement is to add the capability for the speed of the vehicles to beset by the highway. This is a simple additional few bytes of informationthat can be transmitted along with the road edge location map, thus, atvery little initial cost. To account for the tolerances in vehicle speedcontrol systems, the scanning laser radar, or other technology system,which monitors for the presence of vehicles without RtZF™ is also usableas an adaptive cruise control system. Thus, if a faster moving vehicleapproaches a slower moving vehicle, it will automatically slow down tokeep a safe separation distance from the leading, slower moving vehicle.Although the system is not planned for platooning, that will be theautomatic result in some cases. The maximum packing of vehicles isautomatically obtained and thus the maximum vehicle flow rate is alsoachieved with a very simple system.

For the Intelligent Highway System (ITS) application, some provision isrequired to prevent unequipped vehicles from entering the restrictedlanes. In most cases, a barrier will be required since if an errantvehicle did enter the controlled lane, a serious accident could result.Vehicles would be checked while traveling down the road or at atollbooth, or similar station, that the RtZF™ system was in operationwithout faults and with the latest updated map for the region. Onlythose vehicles with the RtZF™ system in good working order would bepermitted to enter. The speed on the restricted lanes would be setaccording to the weather conditions and fed to the vehicle informationsystem automatically, as discussed above.

For ITS use, there needs to be a provision whereby a driver can signalan emergency, for example, by putting on the hazard lights. This wouldpermit the vehicle to leave the roadway and enter the shoulder when thevehicle velocity is below some level. Once the driver provides such asignal, the roadway information system, or the network of vehicle basedcontrol systems, would then reduce the speed of all vehicles in thevicinity until the emergency has passed. This roadway information systemneed not be actually associated with the particular roadway and alsoneed not require any roadway infrastructure. It is a term used here torepresent the collective system as operated by the network of nearbyvehicles and the inter-vehicle communication system. Eventually, theoccurrence of such emergency situations will be eliminated by vehiclebased failure prediction systems such as described in U.S. Pat. No.5,809,437 which is incorporated by reference herein in its entirety.

Enhancements—Vehicle

Emergency situations will develop on intelligent highways. It isdifficult to access the frequency or the results of such emergencies.The industry has learned from airbags that if a system is developedwhich saves many lives but causes a few deaths, the deaths will not betolerated. The ITS system, therefore, must operate with a very highreliability, that is approaching zero fatalities. Since the brains ofthe system will reside in each vehicle, which is under the control ofindividual owners, there will be malfunctions and the system must beable to adapt without causing accidents.

The spacing of the vehicles is the first line of defense. Secondly, eachvehicle with a RtZF™ system has the ability to automatically communicateto all adjacent vehicles and thus immediately issue a warning when anemergency event is occurring. Finally, with the addition of a totalvehicle diagnostic system, such as disclosed in U.S. Pat. No. 5,809,437(Breed), “On Board Vehicle Diagnostic System”, potential emergencies canbe anticipated and thus eliminated with high reliability.

Although the application for ITS envisions a special highway lane andhigh speed travel, the potential exists in the invention to provide alower measure of automatic guidance where the operator can turn controlof the vehicle over to the RtZFrM system for as long as theinfrastructure is available. In this case, the vehicle would operate innormal lanes but would retain its position in the lane and avoidcollisions until a decision requiring operator assistance is required.At that time, the operator would be notified and if he or she did notassume control of the vehicle, an orderly stopping of the vehicle on theside of the road would occur.

For all cases where vehicle steering control is assumed by the RtZF™system, an algorithm for controlling the steering should be developedusing neural networks or neural fuzzy systems. This is especially truefor the emergency cases discussed above where it is well known thatoperators frequently take the wrong actions and at the least, they areslow to react. Algorithms developed by other non-pattern recognitiontechniques do not in general have the requisite generality or complexityand are also likely to make the wrong decisions (although the use of thesame is not precluded in the invention). When the throttle and breakingfunctions are also handled by the system, an algorithm based on neuralnetworks or neural fuzzy systems is even more important.

For the ITS, the driver will enter his or her destination so that thevehicle knows ahead of time where to exit. Alternately, if the driverwishes to exit, he merely turns on his turn signal, which tells thesystem and other vehicles that he or she is about to exit the controlledlane.

Other Features

Blind Spot Detection

The RtZF™ system of this invention also can eliminate the need for blindspot detectors such as disclosed in U.S. Pat. No. 5,530,447 toHenderson. Alternately, if a subset of the complete RtZF™ system isimplemented, as is expected in the initial period, the RtZF™ system canbe made compatible with the blind spot detector described in the '447patent.

Incapacitated Driver

As discussed above, the RtZF™ system of this invention also handles theproblem of the incapacitated driver thus eliminating the need for sleepsensors that appear in numerous U.S. patents. Such systems have not beenimplemented because of their poor reliability. The RtZF™ system sensesthe result of the actions of the operator, which could occur for avariety of reasons including old age, drunkenness, heart attacks, drugsas well as falling asleep.

Emergencies—Car Jacking, Crime

Another enhancement that is also available is to prevent car jacking inwhich case the RtZF™ system can function like the Lojack™ system. In thecase where a car-jacking occurs, the location of the vehicle can bemonitored and if an emergency button is pushed, the location of thevehicle pith the vehicle ID can be transmitted.

Headlight Dimmer

The system also solves the automatic headlight dimmer problem. Since theRtZF™ system equipped vehicle knows where all other RtZF™ systemequipped vehicles are located in its vicinity, it knows when to dim theheadlights. Since it is also interrogating the environment in front ofthe vehicle, it also knows the existence and approximate location of allnon-RtZF™ system equipped vehicles. This is one example of a futureimprovement to the system. The RtZF™ system is a system which lendsitself to continuous improvement without having to change systems on anexisting vehicle.

Rollover

It should be obvious from the above discussion that rollover accidentsshould be effectively eliminated by the RtZF™ system. In the rare casewhere one does occur, the RtZF™ system has the capability to sense thatevent since the location and orientation of the vehicle is known.

For large trucks that have varying inertial properties depending on theload that is being hauled, sensors can be placed on the vehicle thatmeasure the angular and linear acceleration of a part of the vehicle.Since the geometry of the road is known, the inertial properties of thevehicle with load can be determined and thus the tendency of the vehicleto roll over can be determined. Again, since the road geometry is knownthe speed of the truck can be limited to prevent rollovers.

Anticipatory Sensing—Smart Airbags, Evolution of the System

The RtZF™ system is also capable of enhancing other vehicle safetysystems. In particular, through knowing the location and velocity ofother vehicles, for those cases where an accident cannot be avoided, theRtZF™ system will in general be able to anticipate a crash and make anassessment of the crash severity using, for example, neural networktechnology. Even with a limited implementation of the RtZF™ system, asignificant improvement in smart airbag technology results when used inconjunction with a collision avoidance system such as described in Shaw(U.S. Pat. Nos. 5,314,037 and 5,529,138) and a neural networkanticipatory sensing algorithm such as disclosed in U.S. patentapplication Ser. No. 08/247,760 to Breed. A further enhancement would beto code the signal from RtZF™ system equipped vehicles with informationthat includes the size and approximate weight of the vehicle. Then, ifan accident is inevitable, the severity can be accurately anticipatedand the smart airbag tailored to the pending event. Such a device can beimplemented as an RFID tag and made part of the license plate.

It can be seen from the above discussion that the RtZF™ system willevolve in solving many safety, vehicle control and ITS problems. Evensuch technologies as steering and drive by wire will be enhanced by theRtZF™ system in accordance with invention since it will automaticallyadjust for failures in these systems and prevent accidents.

Other Advantages & Enhancements

GPS and Other Measurement Improvements

One of the possible problems with the RtZF™ system described herein isoperation in large cities such as downtown New York. In such locations.unless there are a plurality of local pseudolites or precise positionlocation system installations, the signals from the GPS satellites canbe significantly blocked. Also there is a severe multipath problem. Asolution is to use the LORAN system as a backup for such locations. Theaccuracy of LORAN can be comparable to DGPS. Naturally, the use ofmultiple roadway located precise positioning systems would be a bettersolution or a complementary solution. Additionally, some locationimprovement can result from application of the SnapTrack system asdescribed in U.S. Pat. No. 5,874,914 which is included herein byreference and other patents to Krasner of SnapTrack.

The use of geo-synchronous satellites as a substitute for earth boundbase stations in a DGPS system, with carrier phase enhancements forsub-meter accuracies. is also a likely improvement to the RtZF™ systemthat can have a significant effect in downtown areas.

Another enhancement that would be possible with dedicated satellitesand/or earth bound pseudolites results from the greater control over theinformation transmitted than is available from the GPS system.Recognizing that this system could save up to 40,000 lives per year inthe U.S. alone, the cost of deploying such special purpose stations caneasily be justified. For example, say there exists a modulated wave thatis 10000 kilometers long, another one which is 1000 km long etc. down to1 cm. It would then be easy to determine the absolute distance from onepoint to the other. Other types of modulation are of course possible toachieve the desired result of simply eliminating the carrier integeruncertainty that is discussed in many U.S. patents and other literature.This is not meant to be a recommendation but to illustrate that once thedecision has been made to provide information to every vehicle that willpermit it to always know its location within 10 cm, many technologieswill be there to make it happen. The cost savings resulting fromeliminating fatalities and serious injuries will easily cover the costof such technologies many times over.

Vehicle Enhancements

The RtZF™ system can now be used to improve the accuracy of othervehicle based instruments. The accuracy of the odometer and yaw ratesensors can be improved over time, for example, by regression againstthe DGPS data.

Highway Enhancements

Enhancements to the roadways that result from the use of the RtZF™system include traffic control. The timing of the stoplights can now beautomatically adjusted based on the relative traffic flow. The positionof every vehicle within the vicinity of the light will be known. Whenall vehicles have the RtZF™ system, many stoplights will no longer benecessary since the flow of traffic through an intersection can beaccurately controlled to avoid collisions.

Since the road conditions will now be known to the system, an enhancedRtZF™ system will be able to advise an operator not to travel or,alternately, it can pick an alternate route if certain roads haveaccidents or have iced over, for example. Some people may decide notdrive if there is bad weather or congestion. The important point here isthat sensors will be available to sense the road condition as to bothtraffic and weather, this information will be available automaticallyand not require reporting from weather stations which usually have onlylate and inaccurate information. Additionally, pricing for the use ofcertain roads can be based on weather, congestion, time of day, etc.That is, pricing can by dynamically controlled.

The system lends itself to time and congestion based allocation ofhighway facilities. A variable toll can automatically be charged tovehicles based on such considerations since the vehicle can beidentified. In fact, automatic toll systems now being implemented willlikely become obsolete as will all toll booths.

Finally, it is important to recognize that the RtZF™ system is not a“sensor fusion” system. Sensor fusion is based on the theory that youcan take inputs from different sensors and combine them in such a way asto achieve more information from the combined sensors than from treatingthe sensor outputs independently in a deterministic manner. The ultimatesensor fusion system is based on artificial neural networks, sometimescombined with fuzzy logic to form a neural fuzzy system. Such systemsare probabilistic. Thus there will always be some percentage of caseswhere the decision reached by the network will be wrong. The use of suchsensor fusion, therefore, is inappropriate for the “Zero Fatalities”goal of the invention.

Map Enhancements

Once the road edge and lane locations, and other roadway information,are transmitted to the operator, it requires very little additionalbandwidth to include other information such as the location of allbusinesses that a traveler would be interested in such as gas stations,restaurants etc. which could be done on a subscription basis. Thisconcept was partially disclosed in the '482 patent discussed above andpartially implemented in existing map databases.

Naturally, the communication of information to the operator could bedone either visually or orally as described in U.S. Pat. No. 5,177,685or U.S. provisional patent application Serial No. 60/170,973 filed Dec.15, 1999, both of which are incorporated by reference herein. Finally,the addition of a route guidance system as described in other patentsbecomes even more feasible since the exact location of a destination canbe determined. The system can be configured so that a vehicle operatorcould enter a phone number, for example, or an address and the vehiclewould be automatically and safely driven to that location. Since thesystem knows the location of the edge of every roadway, very little, ifany, operator intervention would be required. Even a cell phone numbercan be used if the cell phone has the SnapTrack GPS location system assoon to be provided by Qualcomm.

Other Uses

The RtZF™ system can even replace other sensors now on or beingconsidered for automobile vehicles including pitch, roll and yawsensors. This information can be found by using carrier phase GPS and byadding more antennas to the vehicle. Additionally, once the system is inplace for land vehicles, there will be many other applications such assurveying, vehicle tracking and aircraft landing which will benefit fromthe technology and infrastructure improvements. The automobile safetyissue and ITS will result in the implementation of a national systemwhich provides any user with low cost equipment the ability to knowprecisely where he is within centimeters on the face of the earth. Manyother applications will undoubtedly follow.

The RtZF™ System

The design of this system is only beginning. From the above discussion,two conclusions should be evident. There are significant advantages inaccurately knowing where the vehicle, the roadway and other vehicles areand that possession of this information is the key to reducingfatalities to zero. Second, there are many technologies that are alreadyin existence that can provide this information to each vehicle. Oncethere is a clear direction that this is the solution then many newtechnologies will emerge. There is nothing inherently expensive aboutthese technologies and once the product life cycle is underway, theadded cost to vehicle purchasers will be minimal. Roadway infrastructurecosts will be minimal and system maintenance costs almost non-existent.

Most importantly, the system has the capability of reducing fatalitiesto zero!

Technical Issues

The accuracy of DGPS has been demonstrated numerous times in smallcontrolled experiments, most recently by the University of Minnesota.

The second technical problem is the integrity of the signals beingreceived and the major cause of the lack of integrity is the multi-patheffect. Considerable research has gone into solving the multi-patheffect and Trimble claims that this problem is no longer an issue.

The third area is availability of GPS and DGPS signals to the vehicle asit is driving down the road. The system is designed to toleratetemporary losses of signal, up to a few minutes. That is the primefunction of the inertial navigation system (INS). Prolonged absence ofthe GPS signal will significantly degrade system performance. There aretwo primary causes of lack of availability, namely, temporary causes andpermanent causes. Temporary causes result from a car driving between twotrucks for an extended period of time, blocking the GPS signals. Theeventual solution to this problem is to change the laws to preventtrucks from traveling on both sides of an automobile. If this remains aproblem, a warning will be provided to the driver that he/she is losingsystem integrity and therefore he/she should speed up or slow down toregain a satellite view. This could also be done automatically.

Permanent blockage of the GPS signals, as can come from operating thevehicle in a tunnel or in the downtown of a large city, can be correctedthrough the use of pseudolites or other guidance systems such as theSnapTrack system or the PPS described here. This is not a seriousproblem since very few cars run off the road in a tunnel or in downtownManhattan.

The final technical impediment is the operation of the diagnostic systemthat verifies that the system is operating properly. This requires anextensive failure mode and effect analysis and the design of adiagnostic system that answers all of the concerns of the FMEA.

Cost Issues

The primary cost impediment is the cost of the DGPS hardware. A singlebase station and roving receiver that will give an accuracy of 2centimeters (1σ) currently costs about $25,000. This is a temporarysituation brought about by low sales volume. Since there is nothingexotic in the receiving unit, the cost can be expected to follow typicalautomotive electronic life-cycle costs and therefore the projected highvolume production cost of the electronics for the DGPS receivers isbelow $100 per vehicle. In the initial implementation of the system, anOmniSTAR™ DGPS system will be used providing an accuracy of 6 cm.

A similar argument can be made for the inertial navigation system.Considerable research and development effort is ongoing to reduce thesize, complexity and cost of these systems. Three technologies are vyingfor this rapidly growing market: laser gyroscopes, fiber-optic lasers,and MEMS systems. The cost of these units today range from a few hundredand ten thousand dollars each, however, once again this is due to thevery small quantity being sold. Substantial improvements are being madein the accuracies of the MEMS systems and it now appears that such asystem will be accurate enough for RtZF™ purposes. The cost of thesesystems in high-volume production is expected to be below ten dollarseach. This includes at least a yaw rate sensor with three accelerometersand probably three angular rate sensors. The accuracy of these units iscurrently approximately 0.003 degrees per second. This is a random errorwhich can be corrected somewhat by the use of multiple vibratingelements. A new laser gyroscope has recently been announced byIntellisense Corporation which should provide a dramatic cost reductionand accuracy improvement.

Eventually when most vehicles on the road have the RtZF™ system thencommunication between the vehicles can be used to substantially improvethe location accuracy, of each vehicle as described above.

The cost of mapping the continental United States (CONUS) is largely anunknown at this time. OmniSTAR has stated that they will map any areawith sufficient detail at a cost of $300 per mile. They have alsoindicated the cost will drop substantially as the number of miles to bemapped increases. This mapping would be done by helicopter using camerasand their laser ranging system. Another method is to outfit a groundvehicle with equipment that will determine the location of the lane andshoulder boundaries of road and other information. Such a system hasbeen used for mapping a Swedish highway. One estimate is that themapping of a road will be reduced to approximately $50 per mile formajor highways and rural roads and a somewhat higher number for urbanareas. The,goal is to map the country to an accuracy of 2 centimeters(1σ).

Related to the costs of mapping is the cost of converting the raw dataacquired either by helicopter or by ground vehicle into a usable mapdatabase. The cost for manually performing this vectorization processhas been estimated at $100 per mile by OmniSTAR. This process can besubstantially simplified through the use of raster to vector conversionsoftware. Such software is currently being used for converting handdrawings into CAD systems, for example. The Intergraph Corp. provideshardware and software for simplifying this task. It is thereforeexpected that the cost for vectorization of the map data will followproportionately a similar path to the cost of acquiring the data and mayeventually reach $10 to $20 per mile for the rural mapping and $25 to a$50 per mile for urban areas. Considering that there are approximatelyfour million miles of roads in the CONUS, and assuming we can achieve anaverage of $150 for acquiring the data and converting the data to a GISdatabase can be achieved, the total cost for mapping all of the roads inUnited States will amount to $600 million. This cost would obviously bespread over a number of years and thus the cost per year is manageableand small in comparison to the $215 billion lost every year due todeath, injury and lost time from traffic congestion.

Another cost factor is the lack of DGPS base stations. The initialanalysis indicated that this would be a serious problem as using thelatest DGPS technology requires a base station every 30 miles. Uponfurther research, however, it has been determined that the OmniSTARcompany has now deployed a nationwide WADGPS system with 6 cm accuracy.The initial goal of the RtZF™ stem was to achieve 2 cm accuracy for bothmapping and vehicle location. The 2 cm accuracy can be obtained in themap database since temporary differential base stations will beinstalled for the mapping purposes. By relaxing the 2 cm requirement to6 cm, the need for base stations every 30 miles disappears and the costof adding a substantial number of base stations is no longer a factor.

The next impediment is the lack of a system for determining when changesare planned for the mapped roads. This will require communication withall highway and road maintenance organizations in the mapped area.

A similar impediment to the widespread implementation of this RtZF™system is the lack of a communication system for supplying map changesto the equipped vehicles.

Educational Issues

A serious impediment to the implementation of this system that isrelated to the general lack of familiarity with the system, is thebelief that significant fatalities and injuries on the U.S. highways area fact of life. This argument is presented in many forms such as “theperfect is the enemy of the good”. This leads to the conclusion that anysystem that portends to reduce injury should be implemented rather thantaking the viewpoint that driving an automobile is a process and as suchit can be designed to achieve perfection. As soon as it is admitted thatperfection cannot be achieved, then any fatality gets immediatelyassociated with this fact. This of course was the prevailing view amongall manufacturing executives until the zero defects paradigm shift tookplace. The goal of the “Zero Fatalities” program is not going to beachieved in a short period of time. Nevertheless, to plan anything shortof zero fatalities is to admit defeat and to thereby allow technologiesto enter the market that are inconsistent with a zero fatalities goal.

Potential Benefits When the System is Deployed

Assumptions for the Application Benefits Analysis

The high volume incremental cost of an automobile will be $200.

The cost of DGPS correction signals will be a onetime charge of $50 pervehicle.

The benefits to the vehicle owner from up-to-date maps and to thepurveyors of services located on these maps. will cover the cost ofupdating the maps as the roads change.

The cost of mapping substantially all roads in the Continental U.S. willbe $600 million.

The effects of phasing in the system will be ignored.

There are 15 million vehicles sold in the U.S. each year.

Of the 40,000 plus people killed on the roadways, at least 10% are dueto road departure, yellow line infraction, stop sign infraction,excessive speed and other causes which will be eliminated by the PhaseZero deployment.

$165 billion are lost each year due to highway accidents.

The cost savings due to secondary benefits will be ignored.

Analysis Methods Described

The analysis method will be quite simple. Assume that 10% of thevehicles on the road will be equipped with RtZF™ systems in the firstyear and that this will increase by 10 percent each year. Ten percent or4000 lives will be saved and a comparable percentage of injuries. Thus,in the first year, one percent of $165 billion dollars will be saved or$1.65 billion. In the second year, this saving will be $3.3 billion andthe third year $4.95 billion. The first-year cost of implementation ofthe system will be $600 million for mapping and $3.75 billion forinstallation onto vehicles. The first year cost therefore will be $4.35billion and the cost for the second and continuing years will be $3.75billion. Thus, by the third year the benefits exceed the costs and bythe 10th year the benefits will reach $16.5 billion compared with costsof $3.75 billion yielding a benefits to cost ratio of more than 4.

Before the fifth year of deployment, it is expected that the other partsof the RtZF™ system will begin to be deployed and that the benefitstherefore are substantially understated. It is also believed that the$250 price for the Phase Zero system on a long-term basis is high and itis expected that the price to drop substantially. No attempt has beenmade to estimate the value of the time saved in congestion or efficientoperation of the highway system. Estimates that have been presented byothers indicate that as much as a two to three times improvement intraffic through flow, is possible. Thus, a substantial portion of the$50 billion per year lost in congestion delays will also be saved whenthe full RRtZF™ system is implemented.

It is also believed that the percentage reduction of fatalities andinjuries has been substantially understated. For the first time, therewill be some control over the drunk or otherwise incapacitated driver.If the excessive speed feature is implemented, then gradually the costof enforcing the nation's speed limits will begin to be substantiallyreduced. Since it is expected that large trucks will be among firstvehicles to be totally covered with the system, perhaps on a retrofitbasis, it is expected that the benefits to commercial vehicle owners andoperators will be substantial. Naturally, the retrofit market mayrapidly develop and the assumptions of vehicles with deployed systemsmay be low. None of these effects have been taken into account in theabove analysis.

The automated highway systems resulting from RtZF implementation isexpected to double or even triple in effective capacity by increasingspeeds and shortening distances between vehicles. Thus, the effect onhighway construction cost could be significant.

Initial System Deployment

The initial implementation of the RtZF™ system would include thefollowing services:

1. A warning is issued to the driver when the driver is about to departfrom the road.

2. A warning is issued to the driver when the driver is about to cross ayellow line or other lane boundary.

3. A warning is provided to the driver when the driver is exceeding asafe speed limit for the road geometry.

4. A warning is provided to the driver when the driver is about to gothrough a stop sign without stopping.

5. A warning is provided to the driver when the driver is about run therisk of a rollover.

6. A warning will be issued prior to a rear end impact by the equippedvehicle.

7. In-vehicle signage will be provided for highway signs.

8. A recording will be logged whenever a warning is issued.

Detailed Description of the Illustrations

FIG. 1 shows the current GPS satellite system associated with the earthand including 24 satellites 2, each satellite revolving in a specificorbital path 4 around the earth. By means of such a GPS satellitesystem, the position of any object can be determined with varyingdegrees of precision as discussed in detail above.

FIG. 2 shows an arrangement of four satellites 2 designated SV₁, SV₂,SV₃ and SV₄ of the GPS satellite system shown in FIG. 1 transmittingposition information to receiver means of a base station 20, such as anantenna 22, which in turn transmits a differential correction signal viatransmitter means associated with that base station, such as a secondantenna 16, to a vehicle 18.

Additional details relating to FIGS. 1-2 can be found in U.S. Pat. No.5.606,506 to Kyrtsos.

FIG. 3 shows an arrangement of four satellites 2 designated SV₁, SV₂,SV₃ and SV₄ of the GPS satellite system as in FIG. 2 transmittingposition information to receiver means of base stations 20 and 21, suchas an antenna 22, which in turn transmit a differential correctionsignal via transmitter means associated with that base stations, such asa second antenna 16, to a geocentric or low earth orbiting (LEO)satellite 30 which in turn transmits the differential correction signalsto vehicle 18. In this case, one or more of the base stations 20,21receives and performs a mathematical analysis on all of the signalsreceived from a number of base stations that cover the area underconsideration and forms a mathematical model of the errors in the GPSsignals over the entire area. For the continental United States, forexample, a group of 13 base stations are operated by OmniStar that aredistributed around the country. By considering data from the entiregroup of such stations, the errors in the GPS signals for the entirearea can be estimated resulting in a position accuracy of about 6-10 cmover the entire area. The corrections are then uploaded to thegeocentric or low earth orbiting satellite 30 for retransmission tovehicles on the roadways. In this way, such vehicles are able todetermine their absolute position to within about 6-10 centimeters. Thisis known as Wide Area Deferential GPS or WADGPS.

The WAAS system is another example of WADGPS for use with airplanes. TheU.S. Government estimates that the accuracy of the WAAS system is about1 meter in three dimensions. Since the largest error is in the verticaldirection, the horizontal error is much less.

FIG. 4 is a logic diagram of the system 50 in accordance with theinvention showing the combination 40 of the GPS and DGPS processingsystems 42 and an inertial reference unit (IRU) or inertial navigationsystem 44. The GPS system includes a unit for processing the receivedinformation from the satellites 2 of the GPS satellite system, theinformation from the satellites 30 of the DGPS system and data from theinertial reference unit (IRU) 44. The inertial reference unit 44contains accelerometers and laser or MEMS gyroscopes.

The system shown in FIG. 4 is a minimal RtZF™ system that can be used toprevent road departure, lane crossing and intersection accidents, whichtogether account for more than about 50% of the fatal accidents in theUnited States.

Map database 48 works in conjunction with a navigation system 46 toprovide a warning to the driver when he or she is about to run off theroad, cross a yellow line, run a stop sign, or run a red stoplight. Themap database 48 contains a map of the roadway to an accuracy of 2 cm (1sigma), i.e., data on the edges of the lanes of the roadway and theedges of the roadway, and the location of all stop signs and stoplightsand other traffic control devices such as other types of road signs.Another sensor, not shown, provides input to the vehicle indicating thatan approaching stoplight is red, yellow or green. Navigation system 46is coupled to the GPS and DGPS processing system 42. For this simplesystem, the driver is warned if any of the above events is detected by adriver warning system 45 coupled to the navigation system 46. The driverwarning system 45 can be an alarm, light, buzzer or other audible noise,or, preferably, a simulated rumble strip for yellow line and “runningoff of road” situations and a combined light and alarm for the stop signand stoplight infractions.

FIG. 5 is a block diagram of the more advanced accident avoidance systemof this invention and method of the present invention illustratingsystem sensors, transceivers, computers, displays, input and outputdevices and other key elements.

As illustrated in FIG. 5, the vehicle accident avoidance system isimplemented using a variety of microprocessors and electronic circuits100 to interconnect and route various signals between and among theillustrated subsystems. GPS receiver 52 is used to receive GPS radiosignals as illustrated in FIG. 1. DGPS receiver 54 receives thedifferential correction signals from one or more base stations eitherdirectly or via a geocentric stationary or LEO satellite. Inter-vehiclecommunication subsystem 56 is used to transmit and receive informationbetween various nearby vehicles. This communication will in general takeplace via broad band or ultra-broad band communication techniques, or ondedicated frequency radio channels. This communication may beimplemented using multiple access communication methods includingfrequency division multiple access (FDMA), timed division multipleaccess (TDMA), or code division multiple access (CDMA) in a manner topermit simultaneous communication with and between a multiplicity ofvehicles. Naturally, other forms of communication between vehicles arepossible such as through the Internet. This communication will consistof such information as the precise location of a vehicle, the latestreceived signals from the GPS satellites in view, other road conditioninformation, emergency signals, hazard warnings, vehicle velocity andintended path, and any other information which is useful to improve thesafety of the vehicle road system.

Infrastructure communication system 58 permits bidirectionalcommunication between the host vehicle and the infrastructure andincludes such information transfer as updates to the digital maps,weather information, road condition information, hazard information,congestion information, temporary signs and warnings, and any otherinformation which can improve the safety of the vehicle highway system.

Cameras 60 are used generally for interrogating environment nearby thehost vehicle for such functions as blind spot monitoring, backupwarnings, anticipatory crash sensing, visibility determination, lanefollowing, and any other visual information which is desirable forimproving the safety of the vehicle highway system. Generally, thecameras will be sensitive to infrared and/or visible light, however, insome cases a passive infrared camera will the used to detect thepresence of animate bodies such as deer or people on the roadway infront of the vehicle. Frequently, infrared or visible illumination willbe provided by the host vehicle.

Radar 62 is primarily used to scan an environment further from thevehicle than the range of the cameras and to provide an initial warningof potential obstacles in the path of the vehicle. The radar 62 can alsobe used when conditions of a reduced visibility are present to provideadvance warning to the vehicle of obstacles hidden by rain, fog, snowetc. Pulsed, continuous wave or micropower impulse radar systems can beused as appropriate. Also Doppler radar can be used to determine theobject to host vehicle relative velocity.

Laser radar 64 is primarily used to illuminate potential hazardousobjects that are in the path of the vehicle. Since the vehicle will beoperating on accurate mapped roads, the precise location of objectsdiscovered by he radar or camera systems can be determined using rangegating and scanning laser radar as described above or phase techniques.

The driver warning system 66 provides visual and audible warningmessages to the driver or others that a hazard exists. In addition toactivating a warning system within the vehicle, this system can activatesound and light systems to warn other people, animals, or vehicles of apending hazardous condition. In such cases, the warning system couldactivate the vehicle headlights, tail lights, horn and/or the vehicle tovehicle, internet or infrastructure communication system to inform othervehicles, a traffic control station or other base station. This systemwill be important during the early stages of implementation of RtZF,however as more and more vehicles are equipped with the system, therewill be less to warn the driver or others of potential problems.

Map database subsystem 68, which could reside on an external memorymodule, will contain all of the map information such as road edges to 2cm accuracy, the locations of stop signs, stoplights, lane markers etc.as described in detail above. The fundamental map data can be organizedon read-only magnetic or optical memory with a read/write associatedmemory for storing map update information. Alternatively, the mapinformation can be stored on rewritable media that can be updated withinformation from the infrastructure communication subsystem 58. Thisupdating can take place while the vehicle is being operated or,alternatively, while the vehicle is parked in a garage or on the street.

Three servos are provided for controlling the vehicle during the laterstages of implementation of the RtZF™ product and include the brakeservo 70, the steering servo 72, and the throttle servo 74. The vehiclecan be controlled using deterministic, fuzzy logic, neural network or,preferably, neural-fuzzy algorithms.

As a check on the inertial system, a velocity sensor 76 based on a wheelspeed sensor, for example, can be provided for the system. Other systemsare preferably used for this purpose such as the GPS/DGPS or preciseposition systems.

The inertial navigation unit, sometimes called the inertial referenceunit or IRU, comprises one or more accelerometers 78 and one or moregyroscopes 80. Usually, three accelerometers would be required toprovide the vehicle acceleration in the latitude, longitude and verticaldirections and three gyroscopes would be required to provide the angularrate about the pitch, yaw and roll axes.

Display subsystem 82 includes an appropriate display driver and either aheads-up or other display system for providing system information to thevehicle operator. The information can be in the form of non-criticalinformation such as the location of the vehicle on a map, as chosen bythe vehicle operator and/or it can consist of warning or other emergencymessages provided by the vehicle subsystems or from communication withother vehicles or the infrastructure. An emergency message that the roadhas been washed out ahead, for example, would be an example of such amessage.

Generally, the display will make use of icons when the position of thehost vehicle relative to obstacles or other vehicles is displayed.Occasionally, as the image can be displayed especially when the objectcannot be identified.

A general memory unit 84 which can comprise read-only memory or randomaccess memory or any combination thereof, is shown. This memory module,which can be either located at one place or distributed throughout thesystem, supplies the information storage capability for the system.

For advanced RtZF™ systems containing the precise positioningcapability, subsystem 86 provides the capability of sending andreceiving information to infrastructure-based precise positioning tagsor devices which may be based on micropower impulse radar technology orRFIR technology or equivalent.

In some locations where weather conditions can deteriorate and degraderoad surface conditions, various infrastructure-based sensors can beplaced either in or adjacent to the road surface. Subsystem 88 isdesigned to interrogate and obtained information from such road-basedsystems. An example of such a system would be an RFID tag containing atemperature sensor. This device may be battery-powered or, preferably,would receive its power from the vehicle-mounted interrogator, or otherhost vehicle-mounted source, as the vehicle passes nearby the device. Inthis manner, the vehicle can obtain the temperature of the road surfaceand receive advanced warning when the temperature is approachingconditions which could cause icing of the roadway, for example. Aninfrared sensor on the vehicle can also be used to determine the roadtemperature and the existence of ice or snow.

In order to completely eliminate automobile accidents, a diagnosticsystem is required on the vehicle that will provide advanced warning ofany potential vehicle component failures. Such a system is described inU.S. Pat. No. 5.809,437 (Breed), incorporated by reference herein.

For some implementations of the RtZF™ system, stoplights mill be fittedwith transmitters which will broadcast a signal when the light is red.This signal can be then received by a vehicle that is approaching thestoplight provided that vehicle has the proper sensor as shown as 92.Alternatively, a camera can be aimed in the direction of stoplights and,since the existence of the stoplight will be known by the system as itwill have been recorded on the map, the vehicle will know when to lookfor a stoplight and determine the color of the light.

Although atomic clocks are probably too expensive to the deployed onautomobiles, nevertheless there has been significant advances recentlyin the accuracy of clocks to the extent that it is now feasible to placea reasonably accurate clock as a subsystem 94 to this system. Since theclock can be recalibrated from each GPS transmission, the clock driftcan be accurately measured and used to predict the precise time eventhough the clock by itself may be incapable of doing so. To the extentthat the vehicle contains an accurate time source, the satellites inview requirement can temporarily drop from 4 to 3.

Naturally, power must be supplied to the system as shown by powersubsystem 96. Certain operator controls are also permitted asillustrated in subsystem 98.

The control processor or central processor and circuit board subsystem100 to which all of the above components 52-98 are coupled, performssuch functions as GPS ranging, DGPS corrections, image analysis, radaranalysis, laser radar scanning control and analysis of receivedinformation, warning message generation, map communication, vehiclecontrol, inertial navigation system calibrations and control, displaycontrol, precise positioning calculations, road condition predictions,and all other functions needed for the system to operate according todesign.

FIG. 6 is a block diagram of the host vehicle exterior surveillancesystem. Cameras 60 are primarily intended for observing the immediateenvironment of the vehicle. They are used for recognizing objects thatcould be most threatening to the vehicle, i.e., closest to the vehicle.These objects include vehicles or other objects that are in the vehicleblind spot, objects or vehicles that are about to impact the mostvehicle from any direction, and objects either in front of or behind thehost vehicle which the host vehicle is about to impact. These functionsare normally called blind spot monitoring and collision anticipatorysensors.

As discussed above, the cameras 60 can use naturally occurring visibleor infrared radiation or they may be supplemented with sources ofvisible or infrared illumination from the host vehicle. The cameras 60used are preferably high dynamic range cameras that have a dynamic rangeexceeding 60 db and preferably exceeding 100 db. Such commerciallyavailable cameras include those manufactured by the Photobit Corporationin California and the IMS Chips Company in Stuttgart Germany.

These cameras are based on CMOS technology and have the importantproperty that pixels are independently addressable. Thus, the controlprocessor may decide which pixels are to be read at a particular time.This permits the system to concentrate on certain objects of interestand thereby make more effective use of the available bandwidth.

Video processor printed circuit boards 61 can be located adjacent andcoupled to the cameras 60 so as to reduce the information transferred tothe control processor. The video processor boards 61 can also performthe function of feature extraction so that all values of all pixels donot need to the sent to the neural network for identificationprocessing. The feature extraction includes such tasks as determiningthe edges of objects in the scene and, in particular, comparing andsubtracting one scene from another to eliminate unimportant backgroundimages and to concentrate on those objects which had been illuminatedwith infrared radiation, for example, from the host vehicle. By theseand other techniques, the amount of information to be transferred to theneural network is substantially reduced.

The neural network 63 receives the feature data extracted from thecamera images by the video processor feature extractor 61 and uses thisdata to determine the identification of the object in the image. Theneural network 63 has been previously trained on a library of imagesthat can involve as many as one million such images. Fortunately, theimages seen from one vehicle are substantially the same as those seenfrom another vehicle and thus the neural network 63 in general does notneed to be trained for each host vehicle type.

Although the neural network 63 has in particular and described above andwill be described in more detail below, other pattern recognitiontechniques are also applicable. One such technique uses the Fouriertransform of the image and utilizes either optical correlationtechniques or a neural network trained on the Fourier transforms of theimages rather than on the image itself. In one case, the opticalcorrelation is accomplished purely optically wherein the Fouriertransform of the image is accomplished using diffraction techniques andprojected onto a display, such as a garnet crystal display, while alibrary of the object Fourier transforms is also displayed on thedisplay. By comparing the total light passing through the display, anoptical correlation can be obtained very rapidly.

The laser radar system 64 is typically used in conjunction with ascanner 65. The scanner 65 is typically comprised of two oscillatingmirrors which cause the laser light to scan the two dimensional angularfield. Alternately, the scanner can be a solid-state device utilizing acrystal having a high index of refraction which is driven by anultrasonic vibrator as discussed above or rotating mirrors. Theultrasonic vibrator establishes elastic waves in the crystal whichdiffracts and changes the direction of the laser light.

The laser beam can be modulated so that the distance to the objectreflecting the light can be determined. The laser light strikes anobject and is reflected back to the same scanning system where it isguided onto a pin diode, or other high speed photo detector. Since thedirection of laser light is known, the angular location of the reflectedobject is also known and since the laser light is modulated the distanceto the reflected point can be determined. By varying modulationfrequency of the laser light, the distance can be very preciselymeasured.

Alternatively, the time-of-flight of a short burst of laser light can bemeasured providing a direct reading of the distance to the object thatreflected the light. By either technique, a three-dimensional map can bemade of the surface of the reflecting object. Objects within a certainrange of the host vehicle can be easily separated out using the rangeinformation. This can be done electronically using a technique calledrange gating, or it can be accomplished mathematically based on therange data. By this technique, an image of an object can be easilyseparated from other objects based on distance from the host vehicle.

Since the vehicle knows its position accurately and in particular itknows the lane on which it is driving, a determination can be made ofthe location of any reflective object and in particular whether or notthe reflective object is on the same lane as the host vehicle. This factcan be determined since the host vehicle has a map and, the reflectiveobject can be virtually placed on that map to determine its location onthe roadway, for example.

The laser radar system will generally operate in the near infrared partof the electromagnetic spectrum. The laser beam will be of relativelyhigh intensity compared to the surrounding radiation and thus even inconditions of fog, snow, and heavy rain, the penetration of the laserbeam and its reflection will permit somewhat greater distanceobservations than the human driver can perceive. Under the RIZF plan, itis recommended that the speed of the host vehicle be limited such thatvehicle can come to a complete stop in one half or less of thevisibility distance. This will permit the laser radar system to observeand identify threatening objects that are beyond the visibility distanceproviding an added degree of safety to the host vehicle.

Radar system 62 is mainly provided to supplement laser radar system. Itis particularly useful for low visibility situations where thepenetration of the laser radar system is limited. The radar system canalso be used to provide a crude map of objects surrounding the vehicle.The most common use for automotive radar systems is for adaptive cruisecontrol systems where the radar monitors the distance and, in somecases, the velocity of the vehicle immediately front of the hostvehicle. The radar system 62 is controlled by the control processor 100.

The display system 82 was discussed previously and can be either a headsup or other appropriate display.

The control processor 100 can be attached to a vehicle special orgeneral purpose bus 110 for transferring other information to and fromthe control processor to other vehicle subsystems.

FIG. 7 shows the implementation of the invention in which a vehicle 18is traveling on a roadway in a defined corridor in the direction X. Eachcorridor is defined by lines 14. If the vehicle is traveling in onecorridor and strays in the direction Y so that it moves along the line22, e.g., the driver is falling asleep, the system on board the vehiclein accordance with the invention will activate a warning. Morespecifically, the system continually detects the position of thevehicle, such as by means of the GPS, DGPS and PPS, and has stored thelocations of the lines 14 defining the corridor. Upon an intersection ofthe position of the vehicle and one of the lines 14 as determined by aprocessor, the system may be designed to sound an alarm to alert thedriver to the deviation or possibly even correct the steering of thevehicle to return the vehicle to within the corridor defined by lines14.

FIG. 8 shows the implementation of the invention in which a pair ofvehicles 18, 26 are traveling on a roadway each in a defined corridordefined by lines 14 and each is equipped with a system in accordancewith the invention. The system in each vehicle 18,26 will receive datainforming it of the position of the other vehicle and prevent accidentsfrom occurring, e.g., if vehicle 18 moves in the direction of arrow 20.This can be accomplished via direct wireless broad band communication,or through another path such as via the Internet or through a basestation. wherein each vehicle transmits its best estimate of itsabsolute location on the earth along with an estimate of the accuracy ofthis location. If one of the vehicles has recently passed a precisepositioning station, for example, then it will know its position sternaccurately to within 2 centimeters, for example. Each vehicle will alsosend the latest satellite messages that it received permitting eachvehicle to precisely determine its relative location to the other sincethe errors in the signals will be the same for both vehicles. To theextent that both vehicles are near each other, even the carrier phaseambiguity can be determined and each vehicle will know its positionrelative to the other to within better than 2 centimeters. As more andmore vehicles become part of the community and communicate theirinformation to each other, each vehicle can even more accuratelydetermine its absolute position and especially if one vehicle knows itsposition very accurately, if it recently passed a PPS for example, thenall vehicles will know their position with approximately the sameaccuracy and that accuracy will be able to be maintained for as long asa vehicle keeps its lock on the satellites in view. If that lock is losttemporarily, the INS system will fill in the gaps and, depending on theaccuracy of that system, the approximate 2 centimeter accuracy can bemaintained even if the satellite lock is lost for up to approximatelyfive minutes.

A five minute loss of satellite lock is unlikely expect in locationswhere buildings or geological features interfere with the signals. Inthe building case, the problem can be eliminated through the placementof PPS stations and the same would be true for the geologicalobstruction case except in remote areas where ultra precise positioningaccuracy is probably not required. In the case of tunnels, for example,the cost of adding PPS stations is very small compared with the cost ofbuilding and maintaining the tunnel.

FIG. 9 is a schematic diagram illustrating a neural network of the typeuseful in image analysis. Data representing features from the imagesfrom the CMOS cameras 60 are input to the neural network circuit 63, andthe neural network circuit 63 is then trained on this data. Morespecifically, the neural network circuit 63 adds up the feature datafrom the CMOS cameras 60 with each data point multiplied by anassociated weight according to the conventional neural network processto determine correlation function.

In this embodiment, 141 data points are appropriately interconnected at25 connecting points of layer 1, and each data point is mutuallycorrelated through the neural network training and weight determinationprocess. In some implementations, each of the connecting points of thelayer 1 has an appropriate threshold value, and if the sum of measureddata exceeds the threshold value, each of the connecting points willoutput a signal to the connecting points of layer 2. In other cases, anoutput value or signal will always be outputted to layer 2 withoutthresholding.

The connecting points of the layer 2 comprises 20 points, and the 25connecting points of the layer 1 are appropriately interconnected as theconnecting points of the layer 2. Similarly, each data value is mutuallycorrelated through the training process and weight determination asdescribed above and in the above referenced neural network texts. Eachof the 20 connecting points of the layer 2 can also have an appropriatethreshold value, if thresholding is used, and if the sum of measureddata exceeds the threshold value, each of the connecting points willoutput a signal to the connecting points of layer 3.

The connecting points of the layer 3 comprises 3 points in this example,and the connecting points of the layer 2 are interconnected at theconnecting points of the layer 3 so that each data is mutuallycorrelated as described above.

The value of each connecting point is determined by multiplying weightcoefficients and summing up the results in sequence, and theaforementioned training process is to determine a weight coefficient Wjso that the value (ai) is a previously determined output.

ai=ΣWj·Xj(j=1 to N)+W ₀

wherein

Wj is the weight coefficient,

Xj is the data

N is the number of samples and

W₀ is bias weight associated with each node.

Based on this result of the training, the neural network circuit 63generates the weights and the bias weights for the coefficients of thecorrelation function or the algorithm.

At the time the neural network circuit 63 has learned from a suitablenumber of patterns of the training data, the result of the training istested by the test data. In the case where the rate of correct answersof the object identification unit based on this test data isunsatisfactory, the neural network circuit 63 is further trained and thetest is repeated. Typically about 200,000 feature patterns are used totrain the neural network 63 and determine all of the weights. A similarnumber is then used for the validation of the developed network. In thissimple example chosen, only three outputs are illustrated. These canrepresent another vehicle, a truck and a pole or tree. This might besuitable for an early blind spot detector design. The number of outputsdepends on the number of classes of objects that are desired. However,too many outputs can result in an overly complex neural network and thenother techniques such as modular neural networks can be used to simplifythe process. When a human looks at a tree, for example, he or she mightthink “what kind of tree is that?” but not “what kind of tiger is that”.The human mind operates with modular neural networks where the object tobe identified is first determined to belong to a general class and thento a subclass etc. Object recognition neural networks can frequentlymake use of this principle with a significant simplification resulting.

In the above example, the image was first subjected to a featureextraction process and the feature data was input to the neural network.In other cases, especially as processing power continues to advance, theentire image is input to the neural network for processing. Thisgenerally requires a larger neural network. Alternate approaches usedata representing the difference between two frames and the input datato the neural network. This is especially useful when a moving object ofinterest is in an image containing stationary scenery that is of nointerest. This technique can be used even when everything is moving byusing the relative velocity as a filter to remove unwanted pixel data.Naturally, any variations on this theme are possible and will now beobvious to those skilled in the art. Alternately, this image can befiltered based on range, which will also significantly reduce the numberof pixels to be analyzed.

In another implementation, the scenes are differenced based onillumination. If infrared illumination is used, for example, theillumination can be turned on and off and images taken and thendifferenced. If the illumination is known only to illuminate an objectof interest then such an object can be extracted from the background bythis technique. A particularly useful method is to turn the illuminationon and off for alternate scan lines in the image. Adjacent scan linescan then be differenced and the resulting image sent to the neuralnetwork for identification.

The neural network can be implemented as an algorithm on a generalpurpose microprocessor or on a dedicated parallel processing DSP, neuralnetwork ASIC or other dedicated parallel processor. The processing speedis generally considerably faster when parallel processors are used andthis can also permit the input of the entire image for analysis ratherthan using feature data. Naturally, a combination of feature and pixeldata can also be used.

Neural networks have certain known defects that various researchers haveattempted to eliminate. For example, if data representing an object thatis totally different from those objects present in the training data isinput to the neural network, an unexpected result can occur which, insome cases, can cause a system failure. To solve this and other neuralnetwork problems, researchers have resorted to adding in some othercomputational intelligence principles such as fuzzy logic resulting in aneural-fuzzy system, for example. As the RtZF™ system evolves, suchrefinements will be implemented to improve the accuracy of the system.Thus, although pure neural networks are currently being applied to theproblem, hybrid neural networks such as modular, ensemble and fuzzyneural networks will undoubtedly evolve.

A typical neural network processing element known to those skilled inthe art is shown in FIG. 10 where input vectors, (X1, X2 . . . Xn) areconnected via weighing elements 120 (W1, W2 . . . Wn) to a summing node130. The output of node 130 is passed through a nonlinear processingelement 140, typically a sigmoid function, to produce an output signal,Y. Offset or bias inputs 125 can be added to the inputs throughweighting circuit 128. The output signal from summing node 130 is passedthrough the nonlinear element 140 which has the effect of compressing orlimiting the magnitude of the output Y.

Neural networks used in the accident avoidance system of this inventionare trained to recognize roadway hazards including automobiles, trucks,and pedestrians. Training involves providing known inputs to the networkresulting in desired. output responses. The weights are automaticallyadjusted based on error signal measurements until the desired outputsare generated. Various learning algorithms may be applied with the backpropagation algorithm with the Delta Bar rule as a particularlysuccessful method.

FIG. 11 shows the implementation of the invention using the PrecisePositioning System (PPS) 151, 152, 153, in which a pair of vehicles 18,26 are traveling on a roadway each in a defined corridor delineated bylines 14 and each is equipped with a system in accordance with theinvention and in particular, each is equipped with PPS receivers. Twoversions of the PPS system will now be described. This invention is notlimited to these two examples but they will serve to illustrate theprincipals involved. Vehicle 18 contains two receivers 160,161 for themicropower impulse radar (MIR) implementation of the invention. MIRtransmitter devices are placed at 151,152 and 153 respectively. They arelinked together with a control wire, not shown, (or possibly a wirelessconnection) such that each device transmits a short radar pulse that aprecise timing relative to the others. These pulses can be sentsimultaneously or at a precise known delay. Vehicle 18 knows from itsmap database the existence and location of the three MIR transmitters.The transmitters 151,152 and 153 can either transmit a coded pulse ornon-coded pulse. In the case of the coded pulse, the vehicle PPS systemwill be able to verify that the three transmitters are in fact the onesthat appear on the map database. Since the vehicle will know reasonablyaccurately it's location and it is, unlikely that other PPS transmitterswill be nearby or within range, the coded pulse may not be necessary.Two receivers 160 and 161 are illustrated on vehicle 18. For the MIRimplementation, only a single receiver is necessary since the positionof the vehicle will be uniquely determined by the time of arrival of thethree MIR pulses. A second receiver can be used for redundancy and alsoto permit the vehicle to determine the angular position of the MIRtransmitters as a further check on the system accuracy. This can be donesince the relative time of arrival of a pulse from one of thetransmitters 151,152,153 can be used to determine is the distance toeach transmitter and by geometry it's angular position relative to thevehicle 18. If the pulses are coded, then the direction to the MIRdevices 151,152,153 will also be determinable.

The micropower impulse radar units require battery or other power tooperate. Since they may be joined together with a wire in order topositively control the timing of the three pulses, a single battery canbe used to power all three units. this battery can also be coupled witha solar panel to permit maintenance free operation of the system. Sincethe MIR devices use very small amounts of power, they can operate formany years on a single battery.

Although the MIR systems are relatively inexpensive, on the order of tendollars each, the installation cost of the system will be significantlyhigher than the RFID solution discussed next. The MIR system is alsosignificantly more complex than the RFFD system; however, its accuracycan be checked by each vehicle that uses the system. Tying the MIRsystem to a GPS receiver and using the accurate clock on the GPSsatellites as the trigger for the sending of the radar pulses can addadditional advantages and complexity. This will permit vehicles passingby to additionally accurately set their clocks to be in synchronizationwith the GPS clocks. Since the MIR system will know its preciselocation, all errors in the GPS signals can be automatically correctedand in that case, the MIR system becomes a differential GPS basestation. For most implementations, this added complexity is notnecessary since the vehicle themselves will be receiving GPS signals andthey will also know precisely their location from the MIR transmittertriad 151,152,153.

A considerably simpler alternate approach to the MIR system describedabove utilizes reflective RFID tags. These tags when interrogated by aninterrogator type of receiver 160,161, reflect a modified RF signal withthe modification being the identification of the tag. Such tags aredescribed in many patents on RFID technology and can be produced forsubstantially less than one dollar each. The implementation of the RFIDsystem would involve the accurate placement of these tags on knownobjects on the infrastructure. These objects could be spots on thehighway, posts, signs, sides of buildings, poles, or structures that arededicated specifically for this purpose. In fact, any structure that isrigid and unlikely to changes position can be used for mounting RFIDtags. In downtown Manhattan, building sides, street lights, stoplights,or other existing structures are ideal locations for such tags. Avehicle 18 approaching a triad of such RFID tags represented by boxes151,152,153 would transmit an interrogation pulse from interrogator 160or 161. The pulse would reflect off of each tag within range and thereflected signal would be received by the same interrogator(s) 160, 161or other devices on the vehicle. Once again, a single interrogator issufficient.

Electronic circuitry, not shown, associated with the interrogator 160 or161 would determine the precise distance from the vehicle to the RFIDtag 151,152,153 based on the round trip time of flight. This willprovide the precise distance is to the three RFID tags 151, 152, 153.Once again, a second interrogator 161 can also be used, in which case,it could be a receiver only and would provide redundancy information tothe main interrogator 160 and also provide a second measure of thedistance to each of the RFID tags. Based on the displacement of the tworeceivers 160, 161, the angular location of each of the RFID tagsrelative into the vehicle can be determined providing further redundantinformation as to the position of the vehicle relative to the tags.

Using the PPS system, a vehicle can precisely determine its locationwithin two centimeters or better relative to the MIR or RFID tags andsince the precise location of these devices has previously been recordedon the map database, the vehicle will be able to determine its preciselocation on the surface of the earth. With this information, the vehiclewill be thereafter able to use the carrier wave phase to maintain itsprecise knowledge of its location until the locks on the satellites arclost. Similarly, the vehicle 18 can broadcast this information tovehicle 26, for example, permitting a vehicle that has not passedthrough the PPS triad to also greatly improve the accuracy with which itknows its position. Each vehicle that has recently passed through a PPStriad now becomes a differential GPS station for as long as thesatellite locks are maintained. Therefore, through inter-vehiclecommunications, all vehicles in the vicinity can also significantlyimprove their knowledge of their position accuracy resulting in a systemwhich is extremely redundant and therefore highly reliable andconsistent with the “Road to Zero Fatalities”™ process. Once this systemis operational, it is expected that the U.S. and other governments willlaunch additional GPS type satellites, or other similar satellites,further strengthening the system and adding further redundancyeventually resulting in a highly interconnected system that approaches100% reliability and, like the Internet, cannot be shut down.

As the system evolves, the problems associated with urban canyons,tunnels, and other obstructions to satellite view will be solved by theplacement of large numbers of MIR systems, RFID tags, or other devicesproviding similar location information.

Although the system has been illustrated for use with automobiles,naturally the same system would apply for all vehicles including trucks,trains an even airplanes taxing on runways. It also would be useful foruse with cellular phones and other devices carried by humans. Thecombination of the PPS system and cellular phones permits the preciselocation of a cellular phone to be determined within centimeters by anemergency operator receiving a 911 call. for example. Such RFID tags canbe inexpensively placed both inside and outside of buildings, forexample.

The range of RFID tags is somewhat limited to approximately 10 metersfor current technology. If there are obstructions preventing a clearview of the RFID tag by the interrogator, the distance becomes less. Forsome applications where it is desirable to use larger distances, batterypower can be provided to the RFID tags. In this case, the interrogatorwould send a pulse to the tag that would turn on the tag and at aprecise time later the tag would transmit an identification message. Insome cases, the interrogator itself can provide the power to drive theRFID circuitry, in which case the tag would again operate in thetransponder mode as opposed to the reflective mode.

From the above discussion, those skilled in the art will think of otherdevices that can be interrogated by a vehicle traveling down the road.Such devices might include radar reflectors, mirrors, other forms oftransponders, or other forms of energy reflectors. All such devices arecontemplated by this invention and the invention is not limited to bespecific examples described.

Any communication device can be coupled with an interrogator thatutilizes the MIR or RFID PPS system described above. Many devices arenow being developed that make use of the Bluetooth communicationspecification. All such Bluetooth enabled devices can additionally beoutfitted with a PPS system permitting the location of the Bluetoothdevice to be positively determined. This enabling technology will permita base station to communicate with a Bluetooth-enabled device whoselocation is unknown and have the device transmit back its preciselocation on the surface of the earth. As long as the Bluetooth-enableddevice is within the range of the base station, its location can beprecisely determine. Thus, the location of mobile equipment in afactory, packages within the airplane cargo section, laptop computers,cell phones. PDAs, and eventually even personal glasses or car keys orany device upon which a Bluetooth enabled deice can be attached can bedetermined. Actually, this invention is not limited to Bluetooth devicesbut encompasses any device that can communicate with any other devices.

Once the location of an object can be determined, many other servicescan be provided. These include finding the device, or the ability toprovide information to that device or to the person accompanying thatdevice such as the location of the nearest bathroom, restaurant, or theability to provide guided tours or other directions to people intraveling to other cities, for example.

FIG. 12a is a flow chart of the method in accordance with the invention.The absolute position of the vehicle is determined at 130, e.g., using aGPS, DGPS PPS system, and compared to the edges of the roadway at 134,which is obtained from a memory unit 132. Based on the comparison at134, it is determined whether the absolute position of the vehicle isapproaching close to or intersects an edge of the roadway at 136. Ifnot, then the position of the vehicle is again obtained, e.g., at a settime interval thereafter, and the process continues. If yes, an alarm orwarning system will be activated or the system will take control of thevehicle (at 140) to guide it to a shoulder of the roadway or other safelocation.

FIG. 12b is another flow chart of the method in accordance with theinvention similar to FIG. 12a. Again the absolute position of thevehicle is determined at 130, e.g., using a GPS, DGPS PPS system, andcompared to the location of a roadway yellow line at 142 (or possiblyanother line which indicates an edge of a lane of a roadway), which isobtained from a memory unit 132. Based on the comparison at 144, it isdetermined whether the absolute position of the vehicle is approachingclose to or intersects the yellow line 144. If not, then the position ofthe vehicle is again obtained, e.g., at a set time interval thereafter,and the process continues. If yes, an alarm will sound or the systemwill take control of the vehicle (at 146) to control the steering orguide it to a shoulder of the roadway or other safe location.

FIG. 12c is another flow chart of the method in accordance with theinvention similar to FIG. 12a. Again the absolute position of thevehicle is determined at 130, e.g., using a GPS, DGPS PPS system, andcompared to the location of a roadway stoplight at 150, which isobtained from a memory unit 132. Based on the comparison at 150, it isdetermined whether the absolute position of the vehicle is approachingclose to a stoplight. If not, then the position of the vehicle is againobtained, e.g., at a set interval thereafter, and the process continues.If yes, a sensor determines whether the stoplight is red (e.g., acamera) and if so, an alarm will sound or the system will take controlof the vehicle (at 154) to control the brakes or guide it to a shoulderof the roadway or other safe location. A similar flow chart can be nowdrawn by those skilled in the art for other conditions such as stopsigns, vehicle speed control, collision avoidance etc.

FIG. 13 illustrates an intersection of a major road 170 with a lesserroad 172. The road 170 has the right of way and stop signs 174 have beenplaced to control the traffic on the lesser road 172. Vehicles 18 and 26arc proceeding on road 172 and vehicle 25 is proceeding on road 170. Avery common accident is caused when vehicle 18 ignores the stop sign 174and proceeds into the intersection where it is struck in the side byvehicle 25 or strikes vehicle 25 in the side.

Using the teachings of this invention, vehicle 18 will know of theexistence of the stop sign and if the operator attempts to proceedwithout stopping, the system will sound a warning and if that warning isnot heeded, the system will automatically bring the vehicle 18 to a stoppreventing it from intruding into the intersection.

Another common accident is where vehicle 18 does in fact stop but thenproceeds forward without noticing vehicle 25 thereby causing anaccident. Since in the fully deployed RtZF™ system, vehicle 18 will knowthrough the vehicle-to-vehicle communication the existence and locationof vehicle 25 and can calculate its velocity, the system can once againtake control of vehicle 18 if a warning is not heeded and preventvehicle from 18 from proceeding into the intersection and therebyprevent the accident.

In the event that the vehicle 25 is not equipped with the RtZF™ system,vehicle 18 will still sense the present of vehicle 25 through the laserradar, radar and camera systems. Once again, when the position andvelocity of vehicle 25 is sensed, appropriate action can be taken by thesystem in vehicle 18 to eliminate the accident.

In another scenario where vehicle the 18 does properly stop at the stopsign, but vehicle 26 proceeds without observing the presence of thestopped vehicle 18, the laser radar, radar and camera systems will alloperate to warn the driver of vehicle 26 and if that warning is notheeded, the system in vehicle 26 will automatically stop the vehicle 26prior to its impacting vehicle 18. Thus, in the scenarios describedabove the “road to zero fatalities”™ system and method of this inventionwill prevent common intersection accidents from occurring.

FIG. 14 is a view of an intersection where traffic is controlled bystoplights 180. If the vehicle 18 does not respond in time to a redstoplight, the system as described above will issue a warning and if notheeded, the system will take control of the vehicle 18 to prevent itfrom entering the intersection and colliding vehicle 25. In this case,the stoplight 180 will either emit a signal indicating its color orvehicle 18 will have a camera mounted such that it can observe the colorof the stoplight. In this case buildings 182 obstruct the view from car18 to car 25 thus an accident can still be prevented even when theoperators are not able to visually see the threatening vehicle.

FIG. 15 illustrates the case where vehicle 18 is about to execute aleft-hand turn into the path of vehicle 25. This accident will beprevented if both cars have the RtZF™ system since the locations andvelocities of both vehicles 18,25 will be known to each other. Ifvehicle 25 is not equipped and vehicle 18 is, then the cam and laserradar subsystems will operate to prevent vehicle 18, turning into thepath of vehicle 25. Thus, once again common intersection accidents areprevented by this invention.

The systems described above can be augmented by infrastructure basedsensing and warning systems. Camera, laser radar or radar subsystemssuch as placed on the vehicle can also be placed at intersections towarn the oncoming traffic if a collision is likely to occur.Additionally, simple sensors that sense the signals emitted by oncomingvehicles, including radar, thermal radiation, etc., can be used tooperate warning systems that notify oncoming traffic of potentiallydangerous situations. Thus, many of the teachings of this invention canbe applied to infrastructure-based installations in addition to thevehicle resident systems.

An important part of this invention is the digital map that containsrelevant information relating to the road on which the vehicle istraveling. The digital map usually includes the location of the edge ofthe road, the edge of the shoulder, the elevation and surface shape ofthe road, the character of the land beyond the road, trees, poles, guardrails, signs, lane markers, speed limits, etc. as discussed in moredetail elsewhere herein. This data or information is acquired in aunique manner for use in the invention and the method for acquiring theinformation and its conversion to a map database that can be accessed bythe vehicle system is part of the invention. The acquisition of the datafor the maps will now be discussed. It must be appreciated though thatthe method for acquiring the data and forming the digital map can alsobe used in other inventions.

Local area differential GPS can be utilized to obtain maps with anaccuracy of 2 cm (one sigma). Temporary local differential stations areavailable from such companies as Trimble Navigation. These localdifferential GPS stations can be placed at an appropriate spacing forthe road to be mapped, typically every 30 kilometers. Once a localdifferential GPS station is placed, it requires several hours for thestation to determine its precise location. Therefore, sufficientstations are required to cover the area that is to be mapped within, forexample, four hours. This may require as many as 10 or more suchdifferential stations for efficient mapping.

A mapping vehicle 200, such as shown in FIGS. 16A, 16B and 17, is usedand the mapping vehicle obtains its location from GPS satellites and itscorrections from the local differential stations. Such a system iscapable of providing the 2 cm accuracy desired for the map database.Typically, at least two GPS receivers 226 are mounted on the mappingvehicle 200. Each GPS receiver 226 is contained within or arranged inconnection with a respective data acquisition module 202, which dataacquisition modules 202 also contain a GPS antenna 204, an accurateinertial measurement unit (IMU) 206, a forward-looking video camera 208,a downward and outward looking linear array camera 210 and a scanninglaser radar 212. The relative position of these components in FIG. 17 isnot intended to limit the invention.

A processor including a printed circuit board 224 is coupled to the GPSreceivers 226, the IMUs 206, the video cameras 208, the linear cameras210 and the scanning laser radars 212. The processor receivesinformation regarding the position of the vehicle from the GPS receivers226, and optionally the IMUs 206, and the information about the roadfrom both linear cameras 210 or from both laser radars 212, or from allof the linear cameras 210 and laser radars 212, and forms the road mapdatabase. Information about the road can also come from one or both ofthe video cameras 208 and be incorporated into the map database.

The map database can be of any desired structure or architecture.Preferred examples of the database structure are of the type disclosedin U.S. Pat. No. 6,144,338 (Davies) and U.S. Pat. No. 6,247,019(Davies), incorporated by reference herein in their entirety.

The data acquisition modules 202 are essentially identical and eachmounts to the vehicle roof on an extension assembly 214 which extendsforward of the front bumper. Extension assembly 214 includes a mountingbracket 216 from the roof of the vehicle 200 forward to each dataacquisition module 210, a mounting bracket 218 extending from the frontbumper upward to each data acquisition module 202 and a cross mountingbracket 220 extending between the data acquisition modules 202 forsupport. Since all of the data acquisition equipment is collocated, itsprecise location is accurately determined by the IMU and thedifferential GPS system.

The forward-looking video cameras 208 provide views of the road as shownin FIG. 18. These cameras 208 permit the database team to observe thegeneral environment of the road and to highlight any anomalies. Theyalso permit the reading of traffic signs and other informationaldisplays all of which will be incorporated into the database. Thecameras 208 can be ordinary color video cameras, high-speed videocameras, wide angle or telescopic cameras, black and white videocameras, infrared cameras, etc. or combinations thereof. In some cases,special filters are used to accentuate certain features. For example, ithas been found that lane markers frequently are more readily observableat particular frequencies, such as infrared. In such cases, filters canbe used in front of the camera lens or elsewhere in the optical path toblock unwanted frequencies and pass desirable frequencies. Polarizinglenses have also been found to be useful in many cases. Normally,natural illumination is used in the mapping process, but for someparticular cases, particularly in tunnels, artificial illumination canalso be used in the form of a floodlight or spotlight that can be at anyappropriate frequency of the ultraviolet, visual and infrared portionsof the electromagnetic spectrum or across many frequencies. Laserscanners can also be used for some particular cases when it is desirableto illuminate some part of the scene with a bright spot. In some cases,a scanning laser rangefinder can be used in conjunction with theforward-looking cameras 204 to determine the distance to particularobjects in the camera view.

The video camera system can be used by itself with appropriate softwareas is currently being done by Lamda Tech International Inc. of Waukesha,Wis., to obtain the location of salient features of a road. However,such a method to obtain accurate maps is highly labor intensive andtherefore expensive. The cameras and associated equipment in the presentinvention are therefore primarily used to supplement the linear cameraand laser radar data acquisition systems to be described now.

The mapping vehicle data acquisition modules will typically contain botha linear camera and a scanning laser radar, however, for someapplications one or the other may be omitted.

The linear camera 210 is a device that typically contains a linear CCD,CMOS or other light sensitive arrays of, for example, four thousandpixels. An appropriate lens provides a field of view to this camera thattypically extends from approximately the center of the vehicle out tothe horizon. This camera records a one-dimensional picture covering theentire road starting with approximately the center of the lane andextending out to the horizon. This linear array camera 210 thereforecovers slightly more than 90 degrees. Typically, this camera operatesusing natural illumination and produces effectively a continuous pictureof the road since it obtains a linear picture, or column of pixels, fortropically every one inch of motion of the vehicle. Thus, a completetwo-dimensional panoramic view of the road traveled by the mappingvehicle is obtained. Since there are two such measurement units, a 180degree view is obtain This camera will typically record in full colorthus permitting the map database team to have a complete view of theroad looking perpendicular from the vehicle. The view is recorded in asubstantially vertical plane. This camera will not be able to read texton traffic signs, thus the need for the forward-looking cameras 208.Automated software can be used with the images obtained from thesecameras to locate the edge of the road, lane markers, the character ofland around and including the road and all areas that an errant vehiclemay encounter. The full color view allows the characterization of theland to be accomplished automatically with minimal human involvement.

The scanning laser radar 212 is typically designed to cover a 90 degreeor less scan thus permitting a rotating mirror to acquire at least foursuch scans per revolution. The scanning laser radar 212 can becoordinated or synchronized with the linear camera so that each coversthe same field of view with the exception that the camera typically willcover more than 90 degrees. Naturally, the scanning laser radar can bedesigned to cover more or less than 90 degrees as desired for aparticular installation. The scanning laser radar can operate in anyappropriate frequency from ultraviolet to the far infrared. Typically,it will operate in the eye-safe portion of the infrared spectrum forsafety reasons. The scanning laser radar 212 can operate either as apulse-modulated or a tone-modulated laser as is known in the art. Ifoperating in the tone-modulated regime, the laser light will betypically modulated with three or more frequencies in order to eliminatedistance ambiguities.

For each scan, the laser radar 212 provides the distance from thescanner to the ground for up to several thousand points in a verticalplane extending from approximately the center of the lane out to nearthe horizon. This device therefore provides precise distances andelevations to all parts of the road and its environment. The preciselocation of signs that were observed with the forward-looking cameras204, for example, can now be easily and automatically retrieved. Thescanning laser radar therefore provides the highest level of mappingautomation.

Scanning laser radars have been used extensively for mapping purposesfrom airplanes and in particular from helicopters where they have beenused to map portions of railway lines in the United States. This is thefirst known use of the scanning laser radar system for mapping roadwayswhere the radar is mounted onto a vehicle that is driving the road.

Ideally, all of the above-described systems are present on the mappingvehicle. Although there is considerable redundancy between the linearcamera and the scanning laser radar, the laser radar operates at oneoptical frequency and therefore does not permit the automaticcharacterization of the roadway and its environment.

As with the forward-looking cameras, it is frequently desirable to usefilters and polarizing lenses for both the scanning laser radar and thelinear camera. In particular, reflections from the sun can degrade thelaser radar system unless appropriate filters are used to block allfrequencies except frequency chosen for the laser radar.

Laser radars are frequently also referred to as ladars and lidars. Allsuch devices that permit ranging to be accomplished from a scanningsystem, including radar, are considered equivalent for the purposes ofthis invention.

A particularly important enhancement to the above-described system usesprecise positioning technology independent of GPS. The precisepositioning system, also known as the calibration system, generallypermits a vehicle to precisely locate itself independently of the IMU orDGPS systems.

One example of this technology involves the use of a radar and reflectorsystem wherein radar transceivers are placed on the vehicle that sendradar waves to reflectors that are mounted at the side of road. Thelocation of reflectors either is already precisely known or isdetermined by the mapping system during data acquisition process. Theradar transceivers transmit a pulse or frequency modulated radar signalto the road-mounted reflectors, typically corner reflectors, whichreflect a signal back to the radar transceiver. This permits the radarsystem to determine the precise distance from the transceiver to thereflector by either time-of-flight or phase methods.

In one possible implementation, each vehicle is equipped with two radardevices operating in the 24-77 GHz spectrum. Each radar unit will bepositioned on the vehicle and aimed outward, slightly forward and uptoward the sides of the roadway. Poles would be positioned along theroadway at appropriate intervals and would have multiple corner cuberadar reflectors mounted thereon to thereto, possibly in a verticalalignment. The lowest reflector on the pole would be positioned so thatthe vehicle radar will illuminate the reflector when the vehicle is inthe lane closest to the pole. The highest reflector on the pole would bepositioned so that the vehicle radar will illuminate the reflector whenthe vehicle is in the lane most remote from the pole. The frequency ofthe positioning of the poles will be determined by such considerationsas the availability of light poles or other structures currently inplace, the probability of losing access to GPS satellites, the densityof vehicle traffic, the accuracy of the IMU and other similarconsiderations. Initially rough calculations have found that a spacingof about ¼ mile would likely be acceptable.

If the precise location of the reflectors has been previously determinedand is provided on a road map database, then the vehicle can use thisinformation to determine its precise location on the road. In the moretypical case, the radar reflectors are installed and the mapping vehicleknows its location precisely from the differential GPS signals and theIMU, which for the mapping vehicle is typically of considerably higheraccuracy then will be present in the vehicles that will later use thesystem. As a result, the mapping vehicle can also map a tunnel, forexample, and establish the locations of radar reflectors that will laterbe used by non-mapping vehicles to determine their precise location whenthe GPS and differential GPS signals are not available. Similarly, suchradar reflectors can be located for an appropriate distance outside ofthe tunnel to permit an accurate location determination to be made by avehicle until it acquires the GPS and differential GPS signals. Such asystem can also be used in urban canyons and at all locations where theGPS signals can be blocked or are otherwise not available. Since thecost of radar reflectors is very low, it is expected that eventuallythey will be widely distributed on the 4 million miles of roads in theU.S.

The use of radar and reflectors for precise positioning is only one ofmany systems being considered for this purpose. Others include markingson roadway, RFID tags, laser systems, laser radar and reflectors,magnetic tags embedded in the roadway, magnetic tape, etc. The radar andreflector technology has advantages over some systems in that it is notseriously degraded by bad weather conditions, is not affected if coveredwith snow, does not pose a serious maintenance problem, and other costand durability features.

The radar transceivers used are typically mounted on either side ofvehicle and pointed upward at between 30 and 60 degrees. They aretypically aimed so that they project across the top of the vehicle sothat several feet of vertical height can be achieved prior to passingover adjacent lanes where the signal could be blocked by the truck, forexample. Naturally, other mounting and aiming systems can be used.

The radar reflectors are typically mounted onto a pole, building,overpass, or other convenient structure. They can provide a return codeby the placement of several such reflectors such that the reflectedpulse contains information that identifies this reflector with aparticular reflector on the map database. This can be accomplished innumerous ways including the use of a collection of radar reflectors in aspaced apart geometric configuration on a radius from the vehicle. Thepresence or absence of a reflector can provide a returned binary code,for example.

The operation of the system is as follows. A vehicle traveling down aroadway in the vicinity of the reflector poles would transmit radarpulses at a frequency of perhaps once per millisecond. These radarpulses would be encoded so that each vehicle knows exactly what radarreturns are from its transmissions. As the vehicle approaches areflector pole, it will begin to receive reflections based on the speedof the vehicle. By observing a series of reflections, the vehiclesoftware can select either the maximum amplitude reflection or theaverage or some other scheme to determine the proper reflection toconsider. The radar pulse will also be modulated to permit a distance tothe reflector calculation to be made based on the phase of the returnedsignal. Thus, as a vehicle travels down the road and passes a pair ofreflector poles, it will be able to determine its longitudinal positionon the roadway based on the pointing angle of the radar devices and thechosen maximum return as described above. It will also be able todetermine its lateral position on the roadway based on the measureddistance from the radar to the reflector.

Each reflector pole will have multiple reflectors determined byintersections of the radar beam from the vehicle traveling in theclosest and furthest lanes. The spacing of reflectors on the pole wouldbe determined by the pixel diameter of the radar beam. For example, atypical situation may require radar reflectors beginning at 4 m from theground and ending at 12 m with a reflector every one-meter. For theinitial demonstrations it is expected that existing structures will beused. The corner cube radar reflectors are very inexpensive so thereforethe infrastructure investment will be small as long as existingstructures can be used. In the downtown areas of cities, buildings etc.can also be used as reflector locations.

To summarize this aspect of the invention, an inexpensive infrastructureinstallation concept is provided which will permit a vehicle to send aradar pulse and receive a reflection wherein the reflection isidentifiable as the reflection from the vehicle's own radar and containsinformation to permit an accurate distance measurement. The vehicle canthus locate itself accurately longitudinally and laterally along theroad.

While the invention has been illustrated and described in detail in thedrawings and the foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the spirit of theinvention are desired to be protected.

We claim:
 1. An arrangement for attaching to a vehicle to enable mappingof a road during travel of the vehicle, comprising: a first dataacquisition module adapted to be arranged on a first side of thevehicle; a second data acquisition module adapted to be arranged on asecond side of the vehicle; each of said modules comprising a GPSreceiver and an antenna for enabling a determination of the position ofthe vehicle to be obtained and a linear camera adapted to provideone-dimensional images of an area on a respective one of the first andsecond sides of the vehicle, said linear cameras providing images of avertical plane perpendicular to the road such that a view of the road ina direction perpendicular to the road is obtained and information aboutthe road is obtainable from that view; and processor means coupled tosaid modules for forming a map database of the road by correlating theposition of the vehicle on the road and the information about the road.2. The arrangement of claim 1, wherein said linear camera in each ofsaid modules comprises at least one of a linear CCD, CMOS and anotherlight sensitive array.
 3. The arrangement of claim 1, wherein saidlinear camera in each of said modules comprises a lens for providing afield of view from an approximate center of the vehicle to the horizonwhereby said linear cameras are adapted to record one-dimensionalpictures covering the entire road starting with approximately the centerof a lane in which the vehicle travels and extending out to the horizon.4. The arrangement of claim 1, wherein each of said modules furthercomprises a scanning laser radar adapted to transmit waves downward in aplane perpendicular to the road and receive reflected radar waves tothereby provide information about distance between said laser radar andthe ground which constitutes information about the road.
 5. Thearrangement of claim 4, wherein in each of said modules, said laserradar is coordinated or synchronized with said linear camera to cover acommon field of view.
 6. The arrangement of claim 4, wherein said laserradars are pulse-modulated or tone-modulated.
 7. The arrangement ofclaim 1, wherein each of said modules further comprises a video cameraadapted to provide images of an area in front of the vehicle wherebyimages of an environment of the road including traffic signs and otherinformational displays are obtained and provide information about theroad.
 8. The arrangement of claim 7, wherein said video camera in eachof said modules is selected from group consisting of color videocameras, high-speed video cameras, wide angle cameras, telescopiccameras, and white video cameras and infrared cameras.
 9. Thearrangement of claim 7, further comprising means for providingartificial illumination at least when an absence of sufficient naturalillumination for obtaining images from said video cameras is detected.10. The arrangement of claim 9, wherein said means for providingartificial illumination comprise a laser scanner adapted to illuminate aparticular part of the area in front of the vehicle with a bright spot.11. The arrangement of claim 7, further comprising a scanning laserrangefinder arranged in connection with at least one of said videocameras for determining the distance to particular objects in the imagesobtained by said at least one video camera whereby the distanceconstitutes information about the road.
 12. The arrangement of claim 1,wherein each of said modules further comprises an inertial measurementunit.
 13. The arrangement of claim 1, further comprising a mountingassembly for mounting said modules to the vehicle.
 14. The arrangementof claim 13, wherein said mounting assembly comprises a mounting bracketfor attaching each of said modules to a roof of the vehicle, a mountingbracket for attaching each of said modules to a front of the vehicle anda mounting bracket for connecting said modules together.
 15. Anarrangement for attaching to a vehicle to enable mapping of a roadduring travel of the vehicle, comprising: a first data acquisitionmodule adapted to be arranged on a first side of the vehicle; a seconddata acquisition module adapted to be arranged on a second side of thevehicle; each of said modules comprising a GPS receiver and an antennafor enabling a determination of the position of the vehicle to beobtained and a scanning laser radar adapted to transmit waves downwardin a plane perpendicular to the road and receive reflected radar wavesto thereby provide information about distance between said laser radarand the ground which constitutes information about the road; andprocessor means coupled to said modules for forming a map database ofthe road by correlating the position of the vehicle on the road and theinformation about the road.
 16. The arrangement of claim 15, whereineach of said modules further comprises a linear camera adapted toprovide one-dimensional images of an area on a respective one of thefirst and second sides of the vehicle, said linear cameras providingimages of a vertical plane perpendicular to the road such that a view ofthe road in a direction perpendicular to the road is obtained andinformation about the road is obtained from that view.
 17. Thearrangement of claim 16, wherein said linear camera in each of saidmodules comprises at least one of a linear CCD, CMOS and another lightsensitive array.
 18. The arrangement of claim 16, wherein said linearcamera in each of said modules comprises a lens for providing a field ofview from an approximate center of the vehicle to the horizon wherebysaid linear cameras are adapted to record one-dimensional picturescovering the entire road starting with approximately the center of alane in which the vehicle travels and extending out to the horizon. 19.The arrangement of claim 16, wherein in each of said modules, said laserradar is coordinated or synchronized with said linear camera to cover acommon field of view.
 20. The arrangement of claim 15, wherein saidlaser radars are pulse-modulated or tone-modulated.
 21. The arrangementof claim 15, wherein each of said modules further comprises a videocamera adapted to provide images of an area in front of the vehiclewhereby images of an environment of the road including traffic signs andother informational displays are obtained and provide information aboutthe road.
 22. The arrangement of claim 21, wherein said video camera ineach of said modules is selected from a group consisting of color videocameras, high-speed video cameras, wide angle cameras, telescopiccameras, black and white video cameras and infrared cameras.
 23. Thearrangement of claim 21, further comprising means for providingartificial illumination at least when an absence of sufficient naturalillumination for obtaining images from said video cameras is detected.24. The arrangement of claim 23, wherein said means for providingartificial illumination comprise a laser scanner adapted to illuminate aparticular part of the area in front of the vehicle with a bright spot.25. The arrangement of claim 21, further comprising a scanning laserrangefinder arranged in connection with at least one of said videocameras for determining the distance to particular objects in the imagesobtained by said at least one video camera whereby the distanceconstitutes information about the road.
 26. The arrangement of claim 15,wherein each of said modules further comprises an inertial measurementunit.
 27. The arrangement of claim 15, further comprising a mountingassembly for mounting said modules to the vehicle.
 28. The arrangementof claim 27, wherein said mounting assembly comprises a mounting bracketfor attaching each of said modules to a roof of the vehicle, a mountingbracket for attaching each of said modules to a front of the vehicle anda mounting bracket for connecting said modules together.
 29. A methodfor mapping a road, comprising the steps of: arranging a first dataacquisition module on a first side of the vehicle; arranging a seconddata acquisition module on a second side of the vehicle, each of themodules comprising a GPS receiver and an antenna and a linear cameraoriented to provide one-dimensional images in a vertical plane of anarea on a respective one of the first and second sides of the vehicle;operating the vehicle on the road while continually obtaining theposition of the vehicle using the GPS receiver and antenna and obtainingimages from the linear cameras of vertical planes perpendicular to theroad; and forming a map database of the road by correlating the positionof the vehicle on the road and information about the road obtained fromthe images from the linear cameras.
 30. The method of claim 29, furthercomprising the step of arranging a lens in connection with each of thelinear cameras to provide a field of view from an approximate center ofthe vehicle to the horizon whereby the video cameras obtainone-dimensional images covering the entire road starting withapproximately the center of the road on which the vehicle travels andextending out to the horizon.
 31. The method of claim 29, furthercomprising the steps of: arranging a scanning laser radar in each of themodules; and while operating the vehicle, transmitting waves from thelaser radars downward in a plane perpendicular to the road and receivingreflected radar waves to thereby provide information about distancebetween the laser radars and the ground which constitutes informationabout the road for use in formation of the map database.
 32. The methodof claim 31, further comprising the step of coordinating orsynchronizing the laser radars and the linear cameras in each of themodules to cover a common field of view.
 33. The method of claim 29,further comprising the steps of: arranging a video camera in each of themodules to provide images of an area in front of the vehicle includingtraffic signs and other informational displays; and while operating thevehicle, obtaining images from the video cameras to thereby provideinformation about the road for use in formation of the map database. 34.The method of claim 33, further comprising the step of arranging ascanning laser rangefinder in connection with at least one of the videocameras for determining the distance to particular objects in the imagesobtained by the at least one video camera.
 35. A method for mapping aroad, comprising the steps of: arranging a first data acquisition moduleon a first side of the vehicle; arranging a second data acquisitionmodule on a second side of the vehicle; each of the modules comprising aGPS receiver and an antenna and a scanning laser radar oriented totransmit waves downward in a plane perpendicular to the road and receivereflected radar waves; operating the vehicle on the road whilecontinually obtaining the position of the vehicle using the GPS receiverand antenna and obtaining information about the distance between thelaser radars and the ground by transmitting and receiving radar waves;and forming a map database of the road by correlating the position ofthe vehicle on the road and the information about distance between thelaser radars and the ground.
 36. The method of claim 35, furthercomprising the steps of: arranging a linear camera in each of themodules; positioning the linear cameras oriented to provideone-dimensional images of a vertical plane of an area on a respectiveone of the first and second sides of the vehicle; and while operatingthe vehicle, obtaining one-dimensional images from the linear cameras tothereby provide information about the road from the images for use information of the map database.
 37. The method of claim 36, furthercomprising the step of arranging a lens in connection with each of thelinear cameras to provide a field of view from an approximate center ofthe vehicle to the horizon whereby the video cameras obtainone-dimensional images covering the entire road starting withapproximately the center of the road on which the vehicle travels andextending out to the horizon.
 38. The method of claim 36, furthercomprising the step of coordinating or synchronizing the laser radarsand the linear cameras in each of the modules to cover a common field ofview.
 39. The method of claim 25, further comprising the steps of:arranging a video camera in each of the modules to provide images of anarea in front of the vehicle including traffic signs and otherinformational displays; and while operating the vehicle, obtainingimages from the video cameras to thereby provide information about theroad for use in formation of the map database.
 40. The method of claim39, further comprising the step of arranging a scanning laserrangefinder in connection with at least one of the video cameras fordetermining the distance to particular objects in the images obtained bythe at least one video camera.